JP4410649B2 - Extruder and molding method - Google Patents

Description

  The present invention relates to an extrusion molding machine and a molding method using the extrusion molding machine, and more particularly to an extrusion molding machine capable of extruding a ceramic honeycomb molded body with high dimensional accuracy and a molding method using the extrusion molding machine. Is.

Conventionally, when extruding ceramics or the like, a plastic material (hereinafter referred to as “kneaded clay” or “kneaded product”) prepared by kneading ceramics fine powder, binder, molding aid, water, etc. at a predetermined ratio and kneading. An auger type extruder that continuously extrudes the clay using a screw is well known as an extruder.
In extrusion molding, residual stress due to a screw appears on a clay that has viscosity, or deformation stress is applied to the ceramics molded body, which may cause minute distortions, cracks, or a slight twist.

Further, among the cracks in the ceramics molded body, a cracking phenomenon at the center of the molded body called a lamination crack is known (Eds. G et al, “Ceramics processing before firing, Chapter 29 Extrusion defects”, published in 1978). The plastic material has a strong metal resistance, and as a result of the collection of small particles for facilitating movement at the interface, the fine particle component in the plastic material tends to collect at the screw contact portion and the barrel contact portion of the extruder. In the molded body, there is no problem because the outer peripheral portion is dispersed, but the central portion is concentrated in one place, so the properties are clearly different from other places, causing a lamination crack.
Furthermore, in the case of a molded body such as a ceramic honeycomb catalyst, the thinner the cross-sectional shape is, the more difficult it is to maintain perfect dimensional accuracy due to the slight residual stress during extrusion molding, as well as during drying. There remains a problem that deformation such as distortion and warpage occurs.

  Japanese Patent Laid-Open No. 2002-254419 (Patent Document 1) discloses an upstream side of the clay flow so that the clay flow can be made smooth and there is no fear of heat generation, and a normal ceramic honeycomb can be extruded even with a thin wall. From the upstream side, the rectification unit is made up of the reduction unit, the cylindrical unit, and the expansion unit in the extruder for ceramic honeycomb, the main part of which is composed of a biaxial screw unit, a rectification unit, a foreign substance removal device unit, and a tip extrusion unit. The biaxial screw portion side inlet shape of the reduced portion is made the same shape as the outlet shape of the biaxial screw portion, and the cylindrical portion side outlet shape of the reduced portion is made the same shape as the inlet shape of the cylindrical portion. A ceramic honeycomb extruder is disclosed in which the shape of the cylindrical portion side inlet is the same shape as the outlet shape of the cylindrical portion, and the foreign matter removing device side outlet shape of the enlarged portion is the same shape as the inlet shape of the foreign matter removing device portion. There.

  Japanese Patent Laid-Open No. 5-253914 (Patent Document 2) discloses that when forming a ceramic clay using an auger type continuous extrusion molding machine, an extruder is provided between the clay supply screw and the forming die. An invention has been disclosed in which a ceramic molded body is formed from a clay without “garbage” by providing a baffle plate having an inclined hole in a direction opposite to the groove direction of the screw.

However, in the above-described conventional extrusion molding machine, when a large-sized catalyst such as an exhaust gas treatment catalyst is extruded, problems such as a large number of cracks (cracks) are generated inside the honeycomb and the catalyst strength is weak. there were.
JP 2002-254419 A JP-A-5-253914

An object of the present invention is to eliminate an extrusion history and a layered structure of an extruded plastic material in a state where a pressure load is small, and to obtain a molded product with less bending, warping, and internal defects, and the extrusion molding thereof It is to provide a molding method using a machine.
In particular, the present invention provides an extrusion molding machine capable of obtaining a honeycomb molded body having a high strength with almost no cracks generated in the molded body even when a ceramic honeycomb molded body having a large shape is extruded. It is providing the shaping | molding method using this.

The present invention provides an extrusion molding machine having a cylindrical rectification unit for adjusting the flow of a plastic material between a supply screw and a molding die, and forming a plurality of flow paths connecting an inlet and an outlet in the rectification unit. Divide the flow of the plastic material and change the plastic material flowing into the central part at the rectifying unit inlet to the peripheral part at the rectifying part outlet, and the plastic material flowing into the peripheral part at the rectifying part inlet into the central part at the rectifying unit outlet. It is characterized by doing.
A flow path for changing the flow from the peripheral part to the central part is formed by a straight pipe group, and the inlet end of the straight pipe group is in contact with the inner wall of the rectifying part at the rectifying part inlet, and the flow path is changed at the outlet of the rectifying part. It is preferable that the outlet ends of the straight pipe group are collectively arranged at the center of the rectifying unit.
It is preferable that the flow path for changing the flow from the peripheral part to the central part is formed on the rectifying part as an axial object by any one of 4 to 16 straight pipe groups.

  The extrusion molding method of the present invention is a method of extruding a plastic material using the extrusion molding machine, and the extrusion molding method of the ceramic honeycomb molded body of the present invention is a ceramic honeycomb molding using the extrusion molding machine. The body is extruded.

According to the extrusion molding machine of the present invention, a molded body having high strength and having no cracks inside can be molded.
Moreover, according to the extrusion molding machine of the present invention, extrusion molding can be performed by setting the internal pressure in the vicinity of the rectifying unit low, and the pressure load on the kneaded product is reduced. Therefore, it is particularly effective for extrusion molding of a plastic material that is easily solidified by water separation with respect to a pressure load. That is, the rotation history and the layered structure of the extruded kneaded product can be eliminated in a state where the pressure load is small, and as a result, bending, warping, and internal defects of the molded product can be prevented.

  In addition, the plastic material is cooled or heated depending on the situation by the molding machine screw and barrel. However, in the case of an auger type extrusion molding machine, a temperature distribution is generated in a plane perpendicular to the extrusion direction, so that the molded body is extruded. However, there was a problem of non-uniformity. However, according to the extrusion molding machine of the present invention, since the plastic material can be mixed without difficulty in the barrel, the temperature distribution becomes small (slow), and the extruded form can be made uniform.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional side view of an essential part of an extrusion molding machine 10 according to the present invention, and a plastic material is supplied from a supply part 12 provided with a supply screw 11 located on the left side of the drawing through a cylindrical rectification part 20. And it flows to the extrusion part 14 in which the shaping | molding die 13 was installed. The supply unit 12, the rectification unit 20, and the extrusion unit 14 are flange-connected.

  In the rectifying unit 20 for adjusting the flow of the plastic material in the present invention, as shown by a plurality of arrows in FIG. 1, a plurality of rectifying unit inlets (aa) and rectifying unit outlets (bb) are connected. A flow path is formed to divide the flow of the plastic material. That is, the plastic material that has flowed into the central part at the rectifying unit inlet (aa) flows out to the peripheral part of the rectifying unit 20 at the rectifying unit outlet (bb). On the other hand, the plastic material that has flowed into the peripheral portion at the rectifying unit inlet (aa) is caused to flow out to the central portion of the rectifying unit 20 at the rectifying unit outlet (bb).

  For example, as shown in FIG. 2, the flow path for dividing the flow of the plastic material is formed by four straight pipes 22, and the straight end 22 a of the straight pipe 22 is connected to the straightening section 20 at the straightening section inlet (aa). The outlet end 22b of the straight pipe 22 is collectively arranged at the center of the rectification unit 20 at the rectification unit outlet (bb). According to the present embodiment, a part of the plastic material supplied to the peripheral portion at the rectifying unit inlet (aa) flows through the straight tube 22 group, and the center of the rectifying unit 20 at the rectifying unit outlet (bb). Collected in the department. On the other hand, the plastic material supplied to the central portion at the rectifying unit inlet (aa) bypasses the outer periphery of the straight tube 22 group and is dispersed at the peripheral portion of the rectifying unit 20 at the rectifying unit outlet (bb). Since the straight tube 22 group is narrowed to the axial center from the rectifying unit inlet (aa) to the rectifying unit outlet (bb), the plastic material supplied to the central part can easily flow toward the peripheral part. ing.

  The plastic material introduced from the supply unit 12 to the rectification unit 20 has a history of the portion that has circulated itself. That is, when the plastic material enters the rectifying unit 20 from the supply unit 12 of the extrusion molding machine 10, the central part (that is, the screw contact portion) and the outermost peripheral edge portion (that is, the barrel contact portion) of the rectifying unit 20 are provided. Small particles in the plastic material tend to gather, and large particles tend to gather in other portions (that is, the intermediate layer between the central portion and the outermost peripheral portion). According to the extrusion molding machine 10 of the present invention, the plastic material can be made homogeneous in the rectifying unit 20, and in particular, the fine particle component at the center that causes the lamination crack can be dispersed. As a result, the history of the plastic material can be eliminated.

The length, diameter, and inclination of the straight pipe 22 are designed in consideration of the properties of the plastic material used. In particular, the flow velocity of the plastic material flowing inside the straight pipe and the plastic material flowing in other portions is the same. It is preferable to do so. Further, it is desirable to reduce the thickness of the straight pipe to such an extent that there is no problem in practical strength.
The number of straight pipes 22 is preferably as large as possible from the viewpoints of the dispersibility of the fine particle component in the central part of the plastic material introduced into the rectifying unit 20 and the homogeneity of the vertical surface in the extrusion direction. 4 to 16, in particular, 4, 8, or 16 in terms of reducing the load on the plastic material and the technical point, it may be arranged so as to be an axial object in the cylindrical rectification unit 20. preferable.
In the example shown in FIG. 2, the outlet end 22 b of the straight tube 22 group cuts the axial center side of the rectifying unit 20 to a short angle of about 30 degrees, thereby smoothing the flow of the plastic material. This angle is preferably in the range of 30-60 degrees.

FIG. 3 shows a modification of the rectifying unit 20. In the present embodiment, as a rectification cassette provided with a flange 23 at the rectification unit inlet (aa), replacement / desorption in the cylindrical rectification unit 20 is facilitated. In this rectification cassette, as shown in the front view (FIG. 3 (1)) and the rear view (FIG. 3 (2)), the straight pipe 24 for changing the flow path from the inlet peripheral portion to the outlet central portion is an axial object. 4 are arranged.
The straight pipe 24 is the same as the embodiment of FIG. 2 except that the cross section has a substantially home base shape. The gap 25 between the straight pipes 24 and 24 is a flow path for changing the flow path of the plastic material from the inlet center to the outlet peripheral edge. A part of the plastic material that has flowed into the peripheral portion of the rectifying unit inlet (aa) flows almost linearly through the gap 25 and is discharged to the peripheral portion of the rectifying unit outlet (bb).
Hereinafter, the present invention will be described more specifically with reference to examples.

Reference example 1

Preparation of kneaded product (a-1) A titanium sulfate solution obtained from the production process of titanium oxide by the sulfuric acid method was thermally hydrolyzed to obtain a metatitanic acid slurry. 22.5 kg of this metatitanic acid slurry was taken out as titanium oxide, charged into a stirring tank equipped with a reflux condenser, and 2.82 kg of ammonium paratungstate was added thereto and mixed, and then 30.5 kg of 15 wt% aqueous ammonia was added to adjust the pH to 9 After adjusting to 0.5, the mixture was aged by heating with sufficient stirring at 95 ° C. for 1 hour. Thereafter, the slurry was taken out by cooling, filtered, dehydrated, and washed to obtain a washed cake having SO ₄ of 0.3 wt% and Na ₂ O of 0.01 wt%. The washed cake was dried at 110 ° C. for 20 hours, and then fired at 550 ° C. for 5 hours to prepare a composite oxide (a) having a TiO ₂ / WO ₃ weight ratio of 90/10.
Next, a solution obtained by dissolving 1.61 kg of ammonium metavanadate in 0.81 kg of monoethanolamine was added to 21.25 kg of the composite oxide (a), then ammonia water was added to adjust the pH of the mixed slurry to 9, and the kneader And kneaded by heating. Further, 1.94 kg of water and glass fiber (hereinafter sometimes abbreviated as GF) and 0.83 kg of clay were added and kneaded for 60 minutes to prepare a kneaded product (a-1).

Using a vacuum extruder (FM-100, manufactured by Miyazaki Tekko Co., Ltd.) in which the rectifying cassette shown in FIG. 3 is incorporated in the rectifying unit 20 having an inner diameter of 105 mmφ, the kneaded product (a-1) has an outer diameter of 73 mm □, It was extruded into a honeycomb shape having an opening of 2.25 mm, a wall thickness of 0.45 mm, and a length of 450 mm. The pressure in the barrel before and after the rectifying unit 20 at the time of molding was measured with the pressure gauge P ₁ and the pressure gauge P ₂ shown in FIG. The measurement results are shown in Table 1.
The obtained molded product was dried at 60 ° C. for 24 hours and then calcined at 500 ° C. for 3 hours, and the composition of TiO ₂ —WO ₃ / V ₂ O ₅ / GF / clay was 85/5/7/3 by weight ratio. A honeycomb catalyst (A-1) having the following characteristics was prepared.
When the honeycomb catalyst (A-1) was cut at the center parallel to the through-hole and the inside was visually observed, no cracks were observed.

Comparative Example 1

In place of the rectifying cassette shown in FIG. 3, a honeycomb rectifying plate made of 23 mm thick steel plate having 151 through holes of 6.1 mmφ was incorporated in the rectifying unit 20 in the same manner as in Example 1, except that A catalyst (B-1) was prepared. Table 1 shows the measurement results of the pressure gauges P ₁ and P ₂ .
When the central part of the honeycomb catalyst (B-1) was cut parallel to the through holes and the inside was visually observed, 45 cracks were observed.

Comparative Example 2

Instead of the rectifying cassette shown in FIG. 3, a rectifying plate in which a flat bar 31 having a width of 23 mm and a thickness of 2 mm is incorporated in a lattice shape at the center of the opening of a steel ring 30 having a thickness of 23 mm as shown in FIG. A honeycomb catalyst (C-1) was prepared in the same manner as in Example 1 except that the rectifying unit 20 was set. Table 1 shows the measurement results of the pressure gauges P ₁ and P ₂ .
When the center of the honeycomb catalyst (C-1) was cut parallel to the through holes and the inside was visually observed, 40 cracks were observed.

Reference example 2

Preparation of the kneaded product (b-1) 21.25 kg of the metatitanic acid slurry as titanium oxide was taken out and charged into a stirring tank equipped with a reflux condenser, and silica sol (SiO ₂ concentration 20 wt%, trade name “Cataloid S-20L” catalyst chemical conversion) (Industry Co., Ltd.) 6.25 kg was added and mixed, then 30.5 kg of 15 wt% aqueous ammonia was added to adjust the pH to 9.5, and sufficient stirring was performed at 95 ° C. for 1 hour. Aged by heating. Next, 2.82 kg of ammonium paratungstate was added, and further heat aging was performed at 95 ° C. for 1 hour. Thereafter, the slurry was taken out by cooling, filtered, dehydrated, and washed to obtain a washed cake having SO ₄ of 0.3 wt% and Na ₂ O of 0.01 wt%. The washed cake was dried at 110 ° C. for 20 hours and then calcined at 650 ° C. for 5 hours to prepare a composite oxide (b) having a TiO ₂ / SiO ₂ / WO ₃ weight ratio of 85/5/10. .
Next, a solution prepared by dissolving 0.23 kg of ammonium metavanadate in 0.25 kg of monoethanolamine was added to a mixture of 19.83 kg of the composite oxide (a) and 3.75 kg of the composite oxide (b). The mixed slurry was adjusted to pH 9 and kneaded by heating with a kneader. Further, 1.39 kg of water and glass fiber (GF) were added and kneaded for 60 minutes to prepare a kneaded product (b-1).

Using a vacuum extrusion molding machine (FM-100, manufactured by Miyazaki Tekko Co., Ltd.) in which the rectifying cassette shown in FIG. 3 is incorporated in the rectifying unit 20 having an inner diameter of 105 mmφ, the kneaded product (b-1) is 80 mm □ in outer diameter, The resultant was extruded into a honeycomb shape having an opening of 6.70 mm, a wall thickness of 1.20 mm, and a length of 450 mm. The pressure in the barrel before and after the rectifying unit 20 at the time of molding was measured with the pressure gauge P ₁ and the pressure gauge P ₂ shown in FIG. The measurement results are shown in Table 1.
The obtained molded product was dried at 60 ° C. for 24 hours and then calcined at 500 ° C. for 3 hours, and the weight ratio of TiO ₂ —WO ₃ / TiO ₂ —WO ₃ —SiO ₂ / V ₂ O ₅ / GF was 79.75. A honeycomb catalyst (A-2) having a composition of 3/15 / 0.7 / 5 was prepared.
FIG. 5A shows a sketch in which the honeycomb catalyst (A-2) is cut at the center in parallel with the through-hole and the inside is realized. Table 1 shows the number of cracks counted from the sketch.

Comparative Example 3

Instead of the rectifying cassette of Example 2, a honeycomb catalyst (B-2) was prepared in the same manner as in Example 2 except that the rectifying plate made of steel plate used in Comparative Example 1 was incorporated in the rectifying unit 20. Table 1 shows the measurement results of the pressure gauges P ₁ and P ₂ .
FIG. 5B shows a sketch in which the honeycomb catalyst (B-2) is cut at the center in parallel with the through hole and the inside is reproduced. Table 1 shows the number of cracks counted from the sketch.

Comparative Example 4

Instead of the rectifying cassette of Example 2, a honeycomb catalyst (C-2) was prepared in the same manner as in Example 2 except that the steel rectifying plate used in Comparative Example 2 was set in the rectifying unit 20. Table 1 shows the measurement results of the pressure gauges P ₁ and P ₂ .
When the center part of the honeycomb catalyst (C-2) was cut in parallel with the through holes and the inside was visually observed, six cracks were observed.

[Table 1]
Honeycomb P ₁ P ₂ crack
(MPa) (MPa) (Location)
Example 1 (A-1) 4.0 3.0 0
Comparative Example 1 (B-1) 4.5 3.1 45
Comparative Example 2 (C-1) 4.1 3.0 40
Example 2 (A-2) 3.0 1.9 0
Comparative Example 3 (B-2) 3.2 2.0 5
Comparative Example 4 (C-2) 3.0 1.9 6

  From the results of Comparative Example 2 and Comparative Example 4, by using a rectifying plate as shown in FIG. 4, the exit speed (flow) of the vertical surface of the plastic material introduced from the supply unit 12 to the rectifying unit 20 is shown. Even when the flat bar 31 was partially adjusted, cracks were generated inside the honeycomb as in the case of the rectifying plate having the uniform through holes used in Comparative Example 1 and Comparative Example 3. I understand.

  The extrusion molding machine of the present invention can be used for extrusion molding of plastics and ceramics. In addition, it is possible to extrude cylinders, columns, prisms, prisms, honeycombs, and other shaped articles.

It is a principal part vertical side view of the extrusion molding machine concerning the present invention. It is internal explanatory drawing of the rectification | straightening part 20 of this invention, aa is an end elevation of a rectification part entrance, bb is an end elevation of a rectification part exit. FIG. 3 (1) is a front view, FIG. 3 (2) is a rear view, FIG. 3 (3) is a front perspective view, and FIG. 3 (4) is a rear perspective view. It is. It is the perspective view which looked at the steel rectifier plate used by the comparative example 2 and the comparative example 4 from the front a little upwards. FIG. 5A is a sketch drawing of the inside of the honeycomb catalyst (A-2), and FIG. 5B is a sketch drawing of the inside of the honeycomb catalyst (B-2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main part of an extrusion molding machine 11 Supply screw 12 Supply part 13 Forming die 14 Extrusion part 20 Straightening part 22 Straight pipe 22a as flow path Inlet end 22b of straight pipe Outlet end 24 of straight pipe Straight pipe 25 as flow path Gaps as flow paths

Claims (4)

In an extrusion molding machine having a cylindrical rectification unit for adjusting the flow of a plastic material between a supply screw and a molding die, a plurality of flow paths connecting an inlet and an outlet are formed in the rectification unit, and the flow of the plastic material Extruders that change the plastic material flowing into the central part at the rectifying unit inlet to the peripheral part at the rectifying part outlet and the plastic material flowing into the peripheral part at the rectifying part inlet into the central part at the rectifying part outlet Because
A flow path for changing the flow from the peripheral portion to the central portion is formed by a straight pipe group, and the inlet end of the straight pipe group is in contact with the inner wall of the rectifying section at the inlet of the rectifying section, and the flow path is changed at the outlet of the rectifying section. An extrusion molding machine characterized in that the outlet ends of the straight tube group are collectively arranged at the center of the rectifying unit . A flow path for changing the flow in the central portion from the peripheral portion, an extrusion molding machine according to claim 1, wherein comprising formed in axial symmetry to the rectifying portion by a straight tube bundle of one plurality of 4 to 16 present. An extrusion molding method for extruding a plastic material using the extrusion molding machine according to claim 1 or 2 . A method for extruding a ceramic honeycomb formed body by extruding a ceramic honeycomb formed body by the method according to claim 3 .

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