JPS62132606A - Method of molding ceramics and carbon material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method of molding refractory materials such as various ceramics and carbon materials using a formwork by vibration molding or impact load molding, and which has excellent a-shape properties. .

The present invention relates to a method for obtaining a uniform molded product with no surface peeling defects, high packing density, and uniformity.

[Problems to be solved by conventional technology and invention]

Ceramic cylinder 2 cylinders or polygonal cylinder.

Examples of methods for molding polygonal columns include slurry casting, extrusion molding, vibration molding, and tamping molding.

By the way, since the slurry casting method uses large-scale water, it is not possible to widen the particle size distribution of the raw material powder, and it is difficult to obtain a thick, high-density, and large-sized molded body.

The extrusion method can only be applied to continuous products with the same cross-sectional shape, and therefore cannot be applied to flanged, bottomed, tapered or thick-walled structures. Furthermore, since the content of water, binder, additives, etc. is high, pores tend to remain inside the molded product, making it difficult to obtain a high-density molded product.

In the vibration molding method and tamping molding method, a split mold of a wooden mold or a metal mold is usually used, but there are the following problems.

1) As the raw materials become densely packed, water and binder move near the boundary between the molded product and the mold and stick or solidify, resulting in poor mold release. Even if it is possible, some of the raw clay will peel off, stick to the formwork, and be carried away, resulting in defects on the surface of the molded body.

2) Conventionally commonly used molding frames are made of metal or hard wood and do not have air permeability, so gases such as air and water vapor in the voids of raw material particles interfere with the filling process. As a result, they collect and remain inside the molded body or at the boundary between the molded body and the formwork, causing defects such as voids and delamination.
There is a predetermined limit to the degree of dense packing that a molded body can reach.
If the packing density of a part of the molded body reaches this limit point, overfilling will occur if the molding operation is not terminated at that point even if other parts with low packing density remain.

Therefore, in the case of large molded products such as long products, there is a problem that the packing density becomes non-uniform.

3) Excessive compaction filling using conventional wooden molds or metal molds may cause the molded product to stick to the mold, making it difficult to release from the mold or causing energy to remain inside the molded product. This accumulates as stress, causing problems such as the molded body expanding and breaking during demolding, or breaking during drying or firing.

4) High-density filling cannot be achieved with the vibration molding method without using water or a binder.

[Means and effects for solving the problem] The present inventors
As a result of extensive research in order to obtain a molded product with good mold releasability, no surface peeling defects, and a uniform packing density using the vibration molding method or the impact load molding method, we have developed A paper frame with specific properties (including the frame used for the outer periphery of the core when forming a cylinder) is interposed between the ceramic or carbon material (also used to include the body) and the ceramic or carbon material. The present invention was made based on the recognition that the object could be achieved by molding. That is, 2. The present invention is characterized in that a vibration molding method uses a molding frame that combines a mold body made of a soft material with water absorption, air permeability, and plastic deformability, and a support having high strength. That is.

A form body made of a soft material is used in combination with a high-strength wooden frame body or a metal frame body that supports the form body in the portion that comes into contact with the raw potted soil. The high-strength support frame in this case also includes a core for forming the cylinder.

The form body made of a soft material must have appropriate water absorption (including oil absorption), air permeability, and plastic deformability as described below.

■Water Absorption As molding progresses, the mold itself absorbs the water containing the binder that moves to the interface between the molded body and the mold in contact with it, keeping the surface of the molded body in a low-moisture state. dripping The water absorption rate or oil absorption rate must be 1% or more, preferably 5% or more. When it is 1% or less, the mold release property is good9
A healthy molded product with no surface defects can be obtained.

■ In order to increase the packing density of the breathable molded body, gas components such as air, water vapor, and gas generated by vaporization of the binder, existing in the voids between the particles of the raw material clay, are removed through the soft material formwork. It is effective to discharge it out of the system. The air permeability must be O,X millidarc or more, preferably 1 millidarcy or more. If it is less than 0.1 mil darcy, coarse pores remain inside or near the surface of the molded product, or two-layer peeling tends to occur. Note that 1 darcy means that 1 milliliter of air permeates per second per 1 cubic centimeter of volume at a pressure difference of 1 square meter/-.

■ Plastic deformability As the packing density of the compact increases, energy (internal stress) accumulates inside the compact.

Expansion occurs when the restraints are released by demolding the formwork. If the molded body is completely restrained by a high-strength, high-rigidity formwork and packed too tightly, a large expansion (called elastic restoring effect) will occur upon demolding, and the molded body will be destroyed. However, in the present invention, as the compact is packed more closely and the energy accumulated inside the compact becomes excessive, the mold itself that restrains the compact deforms slightly to release this excess energy. Then, the close packing operation can be continued. In general, the stress-plastic deformability of a material is given by a stress-strain curve, but since it is difficult to define the appropriate range of the present invention for such two-dimensional properties, the elastic modulus and elastic modulus are used as a guideline instead. In terms of tensile strength, it is preferable that the following value is satisfied.

When dry, elastic modulus when absorbing water: 100 to 5,000 kf/j 50 to 5,000
kf/d tensile strength 50 groan/C- or more 2
Regarding the strength when absorbing water of 0 gin/cJ or more, it is necessary to not cause more than an appropriate amount of deformation with respect to the maximum pressure applied to the mold during molding, and it is necessary to ensure that the two-dimensional correlation between pressure and deformation amount is appropriate. A range exists. That is, in the vibration molding method or the impact load molding method according to the present invention, the voltage is generally 1001 V/ca to 10001' for the raw material clay and the mold.
An instantaneous impact pressure is applied in the range of f/CIA, but
Under such mechanical load conditions, the amount of deformation of the formwork is 0.01
It is desirable that the content be in the range of % to 1%.

Figure 1 shows the appropriate range of deformation.

If the strength during water absorption is low, the dimensional accuracy and dimensional reproducibility of the molded product will deteriorate, and the shearing force generated between the molded product and the mold during molding will cause partial damage to the mold, which can cause damage to the molded product. It also deteriorates the surface finish of the product itself. If the deformation 1 of the formwork is less than 0.01%, it will not be possible to release the stress accumulated inside the molded body due to the dense packing of the raw material clay.
When demolding, elastic expansion of the molded product occurs, causing breakage and internal defects. Furthermore, if the strength is too high, the amount of deformation will be too small, making it impossible to release the stress inside the molded body.

The packing density of the molded body cannot be increased, and the desired dimensional accuracy cannot be obtained.

However, even if the strength of the flexible formwork in contact with the molded body is low upon absorption of water, if shear failure does not occur, excessive deformation can be avoided by using a high-strength support frame in close contact with the formwork.

Examples of soft materials that have the above-mentioned characteristics and can be put to practical use include kraft paper, hard polyurethane sheet, synthetic fiber woven fabric, hard polyethylene sheet, and soft wood. When using these as a molding form, they may be laminated in advance into the desired shape using an appropriate adhesive and molded, or they may be made of a formwork made of a strong material such as metal, wood or synthetic resin. It may be used by pasting it on the inner or outer surface. In this case, the thickness of the soft material may be appropriately selected depending on the shape of the ceramic or refractory material to be molded.1For example, when the outer diameter of the cylindrical molded body is 50 to 600 mm, the thickness of the soft material is 2 to 30 mm.
m, and is formed into a circle, cube, rectangular parallelepiped, polygon, or irregular shape depending on the shape of the desired molded object, and when it is made into a cylindrical shape, an outer frame body and an inner frame body are formed. and use it.

The molding method used in the present invention is generally a vibration molding method or an impact pressure molding method using a pneumatic rammer.

The vibration conditions in the vibration molding method depend on the shape, size, and shape of the molded object.
The weight of the entire formwork is selected as appropriate, but when molding a cylindrical body of 7 tons, for example, with an outer diameter of 80 cm, an inner diameter of 55 cm, and a length of 1200 cm, the upper part of the formwork filled with raw materials is A load weight of 5 to 1 oKt is loaded on the plate, and the formwork is fully loaded onto a damage table adjusted to minimize lateral vibration.Then, the formwork is applied for 5 to 30 minutes at an amplitude of 2 to 6 cm. It is intended to be damaged.

In tamping molding using pneumatic impact consonants, no load weight is used, and the end of the pneumatic impactor is inserted into the mold cavity while filling the raw material clay into the voids between the outer and inner molds to apply impact. Apply pressure. At this time, the pneumatic impactor may be operated manually or automatically by two mechanical operations.

In the present invention, during the curing and drying stage of the molded product after completion of molding, moisture and gaseous molecules are slowly transferred from the molded product to the outside through the soft material having water absorption and air permeability. After molding, the molded product is usually cured at room temperature for 24 hours or more with the soft material mold still in place, and after developing sufficient shape retention strength, the mold is removed.

Then, it is placed in a dryer and dried at a temperature of 30 to 150°C, preferably 40 to 120°C, for 24 hours or more to completely remove moisture and complete curing of the binder.

Note that the soft formwork does not necessarily have to be completely removed; it can be left fixed to the molded body after curing and drying.

Even if the firing process were carried out, there would be no problem in burning it down.

As an embodiment of the method of the present invention, FIG. 1 shows a case where a ceramic cylinder is formed. That is.

Appropriate water absorption inside the metal or wooden mold frame (1)
A paper outer frame body (2) having air permeability and plastic deformation strength is installed in close contact with the outer periphery of a metal or wooden core body (8), which also has appropriate water absorbency 2 air permeability and plastic deformation strength. A paper inner frame body (4) is closely covered, and these are assembled on a metal or wooden base (5) to create a vibration table (6).
The gap between the paper outer frame (2) and the paper inner frame (4) is filled with ceramic raw material clay, and a metal load hoop (7) is inserted from the top to generate vibrations. In addition, after a predetermined period of time, the molded body (8) is removed from the mold outer frame (1) along with the core body (8) with the paper outer frame (2) and paper inner frame (4) still attached. Pull out the core (8).

Next, the molded body (8) is attached to the paper outer frame (2) and the paper inner frame (4).
) and sufficiently curing and drying to develop shape-retaining strength, and then drying thoroughly except for the paper outer frame (2) and the paper inner frame (4) to obtain a sound molded product. .

The raw material clay that can be used as the raw material powder in the method of the present invention includes 1 commonly used materials such as alumina,
Magnesia, zirconia, silica powder, china clay,
Celaox powder like silicon carbide, silicon nitride etc.

There are carbonaceous powders such as graphite powder, coke powder, carbon powder, pitch powder, etc. and metal powders such as silicon powder. 3 to 20 parts by weight, preferably 5 to 15 parts by weight of water per 100 parts by weight of these alone or in a mixture of two or more.

0.05 to 5 parts by weight, preferably 0.5 to 3 parts by weight, of an organic binder such as methyl cellulose, polyvinyl alcohol, diacrylic acid (Xf), phenol resin, heat-treated tar, and further additives. For example, glycerin, Fuchs emulsion, alginate, etc.
Add 1 part of 05-5 weight and mix thoroughly.

Effects By the method of the present invention, the releasability between the molded body and the mold body is significantly improved, pores and defects remaining inside and on the surface of the molded body can be extremely reduced, and the packing density is high. A uniform molded body can be obtained, which is a significant improvement over conventional methods using molds or hard wooden molds.

Next, examples and comparative examples will be described.

Example 1 70 parts by weight of silicon carbide with a particle size of 4w or less and a purity of 98%
゜Metallic silicon powder 30 with a particle size of 5% or more and a particle size of 74 μm or less
7.5 parts by weight of a 10% polyvinyl alcohol aqueous solution were added and thoroughly mixed in a kneader to prepare a ceramic raw clay. On the other hand, with the configuration shown in Figure 2, a metal pedestal (6) is loaded on a vibration table (6), a metal outer frame (1) with an inner diameter of 95 m and a length of 1500 m, water absorption rate of 35%, air permeability rate of Paper tube base paper with 8 mm darcy and tensile strength of 240 kf/- at 9% water absorption, outer diameter 90 m.

A paper outer frame (2) laminated and molded to an inner diameter of 80 m and a length of 1500 m, using the same paper tube base paper to create a frame with an outer diameter of 55 mm and an inner diameter of 50 mm.
A laminated paper core (8) having a length of 1500 mm was assembled.

Next, the gap between the paper outer frame (2) and the paper inner frame (4) of the mold is filled with the ceramic raw material clay.

A metal load shaft (7) with an outer diameter of 79 mm, an inner diameter of 59 m, and a length of 300 mm was inserted from the second part, and vibration molding was performed for 30 minutes at an amplitude of 2 to 5 mm. Next, the molded body (8) is attached to a paper outer frame body (
2) and a metal pedestal (5) together with a paper inner frame body (4),
Remove from the metal outer frame (1) and metal core (8),
After being air-dried at room temperature for 24 hours, it was dried at a maximum temperature of 105°C for 24 hours. After drying, the paper outer frame (2) and the paper inner frame (
The cylindrical molded body obtained by removing 4) has an outer diameter of 80 cm,
It was molded to have an inner diameter of 55 m and a length of 1200 mm. The results obtained are shown in Table 1.

Example 2 70 parts by weight of fused alumina with a particle size of 120 mesh or less,
10 parts by weight of silica sol having a solid content concentration of 30% was added to 30 parts by weight of alumina having an average particle diameter of 80 μm, and thoroughly mixed in a kneader to prepare a ceramic raw clay. On the other hand, the inner surface of the hard wooden outer frame has an outer surface of 200 mm x 200 mm, the inner diameter of 125 m, and the height of 1000 cranes. A rigid polyurethane foam sheet with a rate of 22%2 air permeability of 1 millidarcy, a tensile strength of 5 kg/cd, and a thickness of 2.5 wm is assembled as a formwork for forming a cylindrical body, and between the outer frame body and the core body. While filling the above-mentioned ceramic raw material clay into the void, the tip of an impact pressurizer (rammer) using air pressure was inserted into the void to perform pressure filling.

Next, the molded body was removed from the outer frame and core body, dried at room temperature for 24 hours, and then at a maximum temperature of 105° C. for 24 hours. The results obtained are shown in Table 1.

Example 3 70 parts by weight of artificial graphite powder with a particle size of 8 m or less 1 particle size is 74 μ
Pitch coke powder of 30 m or less.

Then, 5 parts by weight of phenolic resin was added to 9 parts by weight of high softening point pitch powder with a particle size of 74 μm or less, and the mixture was heated in a pressure kneader.
The mixture was thoroughly mixed to prepare a carbonaceous raw material clay. The inner surface of a metal outer cylinder with a one-sided diameter of 545 mm, an inner diameter of 505 m, and a length of 1500 mm, an outer diameter of 395+ai, an inner diameter of 355 m,
A sheet manufactured by laminating kraft paper with a water absorption rate of 90%, air permeability of 40 mdarcy, and a tensile strength of 550 mm/- at 9% water absorption to a thickness of 2.5 vm on the outer surface of a metal inner cylinder with a length of 1500 mm. are assembled as a cylindrical mold by gluing them together, and while filling the above-mentioned carbonaceous material clay into the gap between the outer cylinder and the inner cylinder, the tip of the pneumatic impact pressurizer is inserted into the gap to perform filling molding. A metal core with a diameter of 55 m and a length of 1,500 cm and an inner diameter of 80 m were assembled on a metal pedestal that was set on an imaging stand using the same ceramic raw clay used in Example 1.
Filling the gap between the metal cylindrical outer frame with a thickness of 3 cm and a length of 1500 m. From the top of l-1, the inner diameter is 57 m, the outer diameter is 78 m,
A metal loading weight with a length of 300 m was inserted, and vibration forming was performed for 30 minutes at an amplitude of 2 to 5 m. A two-part mold was used as the metal outer frame in order to facilitate demolding of the molded body, the outer surface of the core bar, and the outer frame. Vibration molding was performed in the same manner as in Example 1 using a raw material clay prepared by adding and mixing 5.5 parts by weight of a 10% polyvinyl aqueous solution to 100 parts by weight of the ceramic raw material. The results obtained are shown in Table 1.

Comparative Example 2 Using the same raw material as the ceramic raw clay used in Example 2, and using the same hard wooden core and hard wooden outer frame as in Example 2, pneumatic impact was applied while directly filling the gap between the two. Rammer molding was performed using a mold. Bulk density is 2.7
When close-packing molding was performed until the temperature became 0 or more, cracks occurred during demolding, and a sound molded product could not be obtained. Table 1 shows the results when the pneumatic impact conditions were relaxed to prevent cracking or adhesion to the frame during demolding.

Comparative Example 3 Using the same carbonaceous raw material clay as in Example 3, and using the same metal inner cylinder and metal outer cylinder as in Example 3, the raw material clay was filled into the gap between the two.

Rammer molding was performed using a pneumatic impactor.

When close-packing molding was performed so that the bulk density of the molded product was 1.80 or more, cracks occurred during demolding, and a healthy molded product could not be obtained.

Table 1 shows the results when the close packing conditions were relaxed to prevent cracking during demolding.

Table 1

[Brief explanation of drawings]

Figure 1 shows the appropriate range of stress deformation of formwork material. Moreover, FIG. 2 shows one embodiment of the method of the present invention. % Pestle applicant: Nippon Light Metal Co., Ltd. Engraving of drawings (no changes to content) Figure 1 Figure 2 Procedural amendment (formality) March 5, 1986 Director General of the Permanent Authority 14! proof of the matter 1985 Special FF Application No. 271603 2. Name of the invention Method of forming ceramics and carbon materials person who makes the five amendments Relationship to the case Patent applicant

Claims (1)

[Claims] In a method of filling a formwork with raw material powder for ceramics and/or carbon material and molding it by vibration forming method or impact load forming method, a formwork body made of a soft material having water absorption, air permeability and plastic deformability and a high A method for molding ceramics and carbon materials, characterized by using a molding frame combined with a support having strength.