JP2014168909A - Method for manufacturing graphite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a graphite material including a filling step capable, by curtailing the occurrence of the local deposition of a raw ingredient powder filled into a molding container or the generation of gaps owing to the mobilization of the powder, of preventing local anisotropy and the generation of a density difference and unlikely to entail cracking.SOLUTION: The provided method for manufacturing a graphite material is a method for manufacturing a graphite material comprising: a filling step of charging, into a molding container, a raw ingredient powder obtained by pulverized an admixture of coke and pitch; a molding step of obtaining a molding by impressing a hydrostatic pressure onto the molding container; a firing step of obtaining a fired product by firing the molding, and a graphitizing step of obtaining a graphite material by graphitizing the fired product. The charging step is executed by a charging device for inserting a tube-shaped charging cylinder having a feeder for feeding the raw ingredient powder and a barrier member for temporarily retaining the raw ingredient powder into the molding container, and charging the raw ingredient powder therein.

Description

  The present invention relates to a method for producing a graphite material.

Graphite materials have heat resistance exceeding 2000 ° C. and chemical stability, and thus are used in various industries.
Graphite material (extruded graphite) produced by extrusion is characterized in that a large material can be easily obtained. However, large-diameter extruded graphite formed by extrusion molding is formed by coarsening raw material particles as it becomes thicker in order to improve moldability. Such a large-diameter extruded graphite has a problem that since the raw material particles are coarse, there are many large pores inside, and stress concentration is likely to occur around the pores, making it difficult to obtain sufficient strength. For this reason, the graphite material obtained by extrusion molding is a material having a characteristic that it is difficult to obtain a large diameter and high strength material.

  On the other hand, the isotropic graphite material is manufactured by forming a CIP (Cold Isostatic Press) using fine raw material powder, firing and graphitizing. Since the raw material is finely pulverized and isotropically pressurized with a CIP molding apparatus, it is characterized in that a high-strength material with a fine structure can be obtained. The isotropic graphite material restricts the size that can be produced mainly by the size of the CIP molding apparatus used for molding. In recent years, large-scale CIP molding apparatuses have been manufactured, and a large graphite material having higher strength than extruded graphite has been obtained. For this reason, it can be widely used as a high-strength internal member of devices such as a hot press, a single crystal pulling device, various high-temperature heating furnaces, heat treatment furnaces, etc., particularly used in a high-temperature inert atmosphere.

While a fine isotropic graphite material having such a structure can provide a high-strength material, it is a problem that the raw material powder tends to segregate because it uses fine raw materials, and is easily cracked in the manufacturing stage. Yes.
In order to solve the segregation when the forming container is filled with the raw powder of the refractory compound, Patent Document 1 proposes the following.
“In order to fill and fill the mold (molding container) with the amount of each refractory compound (raw material) to be filled for CIP molding in the mold (molding container), the intermediate liner is placed in the mold. Positioned along the bar vertically and parallel to the bottom liner, the intermediate liner is positioned above the mold to receive the amount of formulation charged from above the mold, and the intermediate liner is then staged The composition filling method in CIP molding is characterized by receiving a predetermined divided amount of the composition charged at each stage. "

  By adopting such a filling method, “the surface of the refractory compound to be filled is in a free state that is not pressurized, so that a boundary layer is formed at the boundary between the compound to be filled next. And the degree of segregation formed in the refractory blends that are sequentially filled is very small. "

Japanese Patent Laid-Open No. 11-58350

However, in such a method, since it is difficult to take out the intermediate mold in the molding container after filling the raw material powder, it is necessary to perform CIP molding while leaving the intermediate mold in the molding container.
If a jig such as an intermediate mold that does not shrink in volume, even if pressure is applied, is molded while it is placed inside the molding container, the jig will not shrink. The pressure becomes dominant and isotropic pressurization cannot be performed, causing partial anisotropy.

Furthermore, the raw material powder moves together when the intermediate liner is lowered stepwise. At this time, the raw material powder receives a frictional force with the rubber side wall and undergoes shear strain in the longitudinal direction. When the filled raw material powder is subjected to shear strain, voids are generated so that cracks are once formed inside the filled raw material powder.
Further, since the core rod is arranged in the filling container and filled with the raw material powder as it is, when the core rod is pulled out after filling, a gap is once generated around the core rod.
As described above, when a large void is generated in the raw material powder as the raw material powder moves in the molding container, a highly anisotropic raw material such as a graphite material is formed around the portion where there is a void after molding. Orientation or density variation of the raw material powder, which has a different directionality from the surroundings, tends to occur, and becomes a starting point for cracks in the molded body or fired body.
As described above, since it causes cracks, it is not preferable to move the raw material powder of the graphite material once filled inside the molding container.

  Also, the raw powder is filled with coarse powder and fine powder, due to the difference in components, segregation occurs, there is a difference in the shrinkage during firing or graphitization, density difference is formed, causing cracks Become.

  In the present invention, a method for producing a graphite material having a filling step in which generation of segregation and generation of voids due to movement of powder is made difficult to prevent local anisotropy and density difference from occurring and cracks are less likely to occur. The purpose is to provide.

The method for producing a graphite material of the present invention for solving the above problems includes a filling step of filling a raw material powder obtained by kneading and pulverizing coke and pitch into a forming container, and applying a hydrostatic pressure to the forming container. In a method for producing a graphite material, comprising: a molding step for obtaining a calcined product;
In the filling step, a cylindrical filling cylinder having a feeder for supplying raw material powder at the top and a barrier member for once holding the raw material powder inside is inserted into a forming container and filled by a filling device for filling the raw material powder. It is characterized by that.

A large container for obtaining a large-sized graphite material is required. It has been found that when raw powder is dropped and filled in air into a large molded container, segregation is likely to occur for the following reasons.
(1) In addition to the pulsation caused by the screw of the feeder, uneven supply of the raw powder due to the starting and stopping of the feeder is likely to occur.
(2) A difference in drop speed is caused by a difference in air resistance with respect to the particle diameter. In other words, uneven supply of the raw powder occurs, and segregation occurs in the process of the raw powder falling in the air.

  According to the present invention, a filling device that inserts a cylindrical filling cylinder having a feeder that supplies raw material powder into the upper portion and a barrier member that temporarily holds the raw material powder into the inside of the forming container and is filled with the raw material powder. Filled. For this reason, even if pulsation occurs in the raw material powder supplied from the feeder, the raw material powder is once held by the barrier member inside the filling cylinder, and when the fixed amount of accumulated raw material powder falls together, The pulsation of the raw material powder can be absorbed.

Further, since the filling cylinder is inserted into the molding container, the distance from the barrier member inside the filling cylinder to the dropping into the molding container can be shortened. For this reason, it is possible to minimize the segregation caused by the difference in dropping speed due to the air resistance of the raw material powder falling from the filling cylinder.
Furthermore, since the filling cylinder is taken out after filling and no jig is left in the molding container, it is difficult to damage the molding container and anisotropy of the graphite material can be prevented.
The raw material powder is filled in order from the bottom of the forming container and is not easily affected by the supply powder of the raw material powder, so that segregation is unlikely to occur, and there is no movement of the powder that causes voids in the raw material powder after filling. Since it is difficult to form a place where different pressure is applied, local anisotropy is not formed, and cracks in the molding process, firing process or graphitization process can be prevented.

It is a process flowchart which shows the manufacturing process of the manufacturing method of the graphite material of this invention. It is explanatory drawing which shows the filling apparatus of Embodiment 1 of the manufacturing method of the graphite material of this invention. It is explanatory drawing which shows the filling apparatus of Embodiment 2 of the manufacturing method of the graphite material of this invention. It is explanatory drawing which shows the filling apparatus used in Example 1 of the manufacturing method of the graphite material of this invention. It is explanatory drawing which shows a mode until raw material powder accumulates on the barrier member of the manufacturing method of the graphite material of this invention, and falls. The modification of the barrier member of the manufacturing method of the graphite material of the present invention is shown.

The method for producing a graphite material according to the present invention includes a filling step of filling raw powder obtained by kneading and pulverizing coke and pitch into a molding container, a molding step of applying a hydrostatic pressure to the molding container to obtain a molded body, and molding. In a method for producing a graphite material comprising: a firing step for firing a body to obtain a fired body; and a graphitization step for graphitizing the fired body to obtain a graphite material,
In the filling step, a cylindrical filling cylinder having a feeder for supplying raw material powder at the top and a barrier member for once holding the raw material powder inside is inserted into a forming container and filled by a filling device for filling the raw material powder. It is characterized by that.

Next, the detail of the manufacturing method of the graphite material of this invention is demonstrated.
FIG. 1 is a process flow diagram showing a production process of a method for producing a graphite material of the present invention.

The manufacturing method of the graphite material of the manufacturing method of this invention consists of the following processes.
(S1) Filling step of filling raw powder obtained by kneading and pulverizing coke and pitch into a molding container (S2) Molding step of applying a hydrostatic pressure to the molding container to obtain a molded body (S3) Firing and firing the molded body Firing step for obtaining a body (S4) Graphitizing step for graphitizing the fired body to obtain a graphite material The method for producing a graphite material of the production method of the present invention is particularly characterized in the filling step (S1), and the molding step (S2). In combination with the firing step (S3) and the graphitization step (S4), local anisotropy, local density variation and segregation can be prevented, and cracks can be prevented in the molding step, firing step or graphitization step. It is possible to provide a method for producing a graphite material having a filling step capable of preventing generation.

  Next, each step will be described.

<Filling process>
The raw material powder obtained by kneading and pulverizing the coke and pitch of the present invention will be specifically described.

The coke for obtaining the raw material powder of the production method of the present invention is not particularly limited and may be any type. Either petroleum-based coke made from crude oil or coal-based coke made from coal can be used. The coke may be raw coke or calcine coke obtained by calcining raw coke.
In the case of coal-based coke, coal itself may be used, but coal-based raw coke obtained by coking tar pitch obtained from coal, and coal-based calcine obtained by calcining coal-based raw coke. Coke etc. can be used. When coal-based coke that passes through tar pitch is used, it is possible to obtain a high-purity graphite material without contamination by foreign matters.

In the case of petroleum coke, petroleum-based raw coke obtained by coking crude oil residue, petroleum-based calcine coke obtained by calcining petroleum-based raw coke, and the like can be used.
Coke can be used after being pulverized. The median diameter of the pulverized coke is not particularly limited, but is preferably pulverized to a median diameter of 1 to 40 μm, for example. When the median diameter of coke is 1 μm or more, the amount of pitch used for kneading can be reduced, so that the volatile content of the obtained raw material powder can be reduced, and cracks are generated during subsequent firing. Can be difficult. When the median diameter of the coke is 40 μm or less, the pore size of the obtained graphite material can be reduced. Therefore, stress concentration hardly occurs around the pores, and a high-strength graphite material can be obtained. A more preferable median diameter range is 5 to 20 μm. When the median diameter of the coke is 5 μm or more, the amount of pitch used for kneading can be further reduced, so that the volatile content of the obtained raw material powder can be further reduced, and cracks can occur during subsequent firing. Can be made difficult to occur. When the median diameter of coke is 20 μm or less, the pore size of the obtained graphite material can be further reduced, so that stress concentration does not easily occur around the pores, and a graphite material with higher strength can be obtained. .
The median diameter means a 50% volume cumulative diameter and can be measured with a laser diffraction particle size measuring apparatus.

  Coke can be ground by any method. Either dry pulverization or wet pulverization may be used, but dry pulverization is easier to use because subsequent drying is unnecessary. Dry pulverization may be performed by any pulverizer. As the pulverizer, for example, a hammer mill, a pin mill, a roller mill, a jet mill or the like can be used, and is not particularly limited.

The pitch for obtaining the raw material powder of the production method of the present invention is not particularly limited. Either petroleum-based pitch made from crude oil or coal-based coke made from coal can be used.
The softening point of the pitch for obtaining the raw material powder of the production method of the present invention is not particularly limited. The pitch is classified into a soft pitch, a medium pitch, a hard pitch, etc. according to the softening point, and any of them can be used. The soft pitch has a softening point of 70 ° C or lower, the intermediate pitch has a softening point of 70 to 85 ° C, and the intermediate pitch has a softening point of 85 ° C or higher. The range of the preferable softening point of the pitch for obtaining the raw material powder of the present invention is 60 to 150 ° C. When the pitch softening point is 60 ° C. or higher, a large amount of a high molecular weight component is contained, so that the carbonization yield is high, so that generation of cracking gas is small during firing, and cracks can be hardly generated. When the pitch softening point is 150 ° C. or lower, the pitch can be sufficiently melted in the kneading step, and the surface of the coke particles can be kneaded so as to cover the pitch. For this reason, the caking property of raw material powder can be ensured, and it can combine strongly in a formation process and a baking process, and can make it hard to generate | occur | produce a crack.

  In the present specification, caking is a term used particularly for coal and carbon-based materials. The caking property means a property that can be carbonized through a softened state, and can be bonded to each other because they are sticky in the softened state. ing.

The method of kneading the pitch and coke in the production method of the present invention is not particularly limited, and can be performed, for example, as follows.
The ground coke is put into a kneader. The temperature of the kneader is heated above the softening point of the pitch to be added. The heating may be performed in advance before the coke is added, or may be performed after the coke is charged.
Next, the pitch is input. The pitch may be a melt pitch heated above the softening point, or may be a solid pitch that is not heated. The solid pitch includes flaky pitch, massive pitch, and the like. The order in which the pitch and coke are introduced is not particularly limited, but may be the same as the pitch and coke, or may be introduced after the coke is introduced.
When pitch is added and then kneaded with a kneader, the pitch is covered with coke powder. The obtained kneaded product of pitch and coke is discharged from the kneader.

  Next, raw material powder can be obtained by pulverizing the kneaded product. The kneaded product can be pulverized by dry pulverization. The median diameter of the raw material powder obtained is desirably larger than the median diameter of coke. Since the raw material particles are composed of coke coated with pitch and a plurality of cokes combined, the pitch of the raw material powder is pulverized so that the median diameter of the obtained raw material powder is larger than the median diameter of the coke. It is possible to prevent the surface of the coke covered with water from being exposed, and to prevent the caking property from decreasing.

  Although the preferable median diameter of the raw material powder of the manufacturing method of this invention is not specifically limited, For example, it is 5-50 micrometers. When the median diameter of the raw material powder is 5 μm or more, the gap between the raw material powders constituting the molded body is large, so that the decomposition gas generated during firing can be easily removed, and cracks can be hardly generated. When the median diameter of the raw material powder is 50 μm or less, the raw material powder is bonded, and the pores of the graphite material obtained by carbonization and graphitization can be reduced, so stress concentration does not easily occur around the pores, and high strength A graphite material can be obtained. A more preferable median diameter of the raw material powder is 15 to 40 μm. When the median diameter of the raw material powder is 15 μm or more, since the gap between the raw material powders constituting the molded body is large, the decomposition gas generated during firing can be more easily removed, and cracks can be further prevented from being generated. When the median diameter of the raw material powder is 40 μm or less, the raw material powder is bonded, and the pores of the graphite material obtained by carbonization and graphitization can be further reduced. A strong graphite material can be obtained.

  Types of coke and pitch for obtaining raw material powder of the production method of the present invention, coke pulverization, type of pulverizer for pulverizing coke, median diameter of coke, method of kneading, method of pulverizing kneaded product, kneaded product The type of pulverizer to be pulverized and the median diameter of the raw material powder may be combined in any way, and can be used as a combined raw material powder as appropriate.

The molded container of the production method of the present invention will be described.
The molding container of the manufacturing method of the present invention is a container for use in the molding process, which is the next process, by filling the raw material powder inside and applying hydrostatic pressure with a CIP molding apparatus using a liquid pressure medium. A molded body can be obtained. Therefore, the molded container is made of a material having airtightness and flexibility that can be freely deformed.
The material of the molded container of the production method of the present invention is preferably a resin material, and for example, rubber, elastomer, polyolefin, polyester and the like can be used. The thickness of the molded container is not particularly limited as long as the pressure medium can be prevented from entering. For example, the thing of the thickness of 0.1-30 mm can be used.

  The molded container of the production method of the present invention can be sealed with a cover. By covering and sealing the molding container with the lid, it is possible to prevent the pressure medium from entering the inside of the CIP molding apparatus. For this reason, the filled raw material powder is molded without contacting the pressure medium, and can form a molded body.

  The size of the molded container of the production method of the present invention is not particularly limited, but can be suitably applied to the production of particularly large graphite materials. For example, in the case of a molded container having a height of 1000 to 3000 mm and a cylindrical cavity, the inner diameter is, for example, 500 to 2500 mm, and in the case of a molded container having a cubic cavity, each of two orthogonal sides of the bottom surface The length is, for example, 500 to 2000 mm, and the lengths of two orthogonal sides of the bottom surface may be the same or different. The molding container has an opening on the upper side and can be filled with raw material powder from above.

The molded container of the production method of the present invention may be used by inserting it into a metal or resin container if it is difficult to stand on its own. By inserting the container into the container, the molded container can be prevented from being deformed by gravity, and the lower part of the molded container can be prevented from expanding due to the pressure of the filled raw material powder.
The method for sealing the molded container in the production method of the present invention may be any method and is not particularly limited. A method of sealing with an adhesive tape, a method in which a molded container and a lid are each provided with a flange, a method of sealing with an O-ring, a method of bonding a molded container and a lid, a molding container and a lid are overlapped, a rubber band, etc. Any method can be used, such as a method of tightening with a fastener.

The filling apparatus of the manufacturing method of the present invention will be described.

  The raw material powder is composed of particles having various particle diameters and does not have a single peak particle size distribution. The raw material powder contains coke. Coke has a high orientation, so when it is pulverized, it is easily pulverized into scales and needles, and the aspect ratio becomes high. When the raw material powder having such characteristics is dropped in the air, fine particles and particles with a large aspect ratio fall slowly, and large particles and particles with a small aspect ratio fall quickly due to the action of air resistance. Such an action is more likely to occur as the height of the fall increases. For this reason, a tall molded container has such a factor that such a drop speed difference is likely to occur.

  In addition, the raw material powder obtained by kneading coke and pitch has a different pitch ratio as a binder as compared with coarse particles and fine particles. When segregation occurs, the coke and pitch ratio tends to vary. In particular, fine raw material powder particles are small in coke particles and large in specific surface area, so that the ratio of pitch is high and cracking gas is likely to be generated in the subsequent firing step. For this reason, if the area | region where the particle | grains of the fine raw material powder gathered unevenly, the area | region which tends to generate | occur | produce decomposition gas will be unevenly distributed in the obtained graphite material, and it will become easy to produce variation in bulk density. In addition, since a region having a large pitch serving as a binder is unevenly distributed, variations in firing shrinkage and graphitization shrinkage are likely to occur. These variations cause cracks.

  The raw material powder supplied from the feeder to the forming container is not always supplied continuously. When the supply of the raw material powder is interrupted, segregation is likely to occur due to the difference in the falling speed of the raw material powder. Further, even when there is a pulsation in the supply of raw material powder, segregation is likely to occur due to the difference in the falling speed of the raw material powder.

When the raw material powder supplied from the feeder to the forming container is not continuously supplied, for example, when the filling device is started at the start of filling, when the filling device is stopped at the end of filling, the raw material powder in the storage tank For example, when the feeder is temporarily stopped due to problems such as the bridging phenomenon and the filling device, the rotation of the feeder is slow and the supply of raw material powder is pulsating. The feeder is constituted by conveying means such as a screw and a bucket. Since these conveying means convey the raw material powder by dividing a certain amount of the raw material powder into a plurality of times, the pulsation of the raw material powder becomes remarkable. In the case of a feeder using a screw, since the raw material powder is transported by the blades of the screw, when comparing the front side and the rear side with respect to the traveling direction of the blades, there is a lot of raw material powder on the front side, and in the traveling direction of the blades On the other hand, the difference in the amount of raw material powder between the front side and the rear side causes pulsation.
The bridging phenomenon refers to a phenomenon in which the raw material powder particles are blocked by forming an arch structure at the outlet of the tank, and the powder is not discharged from the discharge port.

The filling device of the manufacturing method of the present invention includes a cylindrical filling cylinder having a feeder for supplying raw material powder at an upper portion and a barrier member for once holding the raw material powder therein, and the raw material powder is inserted into the molding container. It is characterized by filling.
The filling cylinder of the manufacturing method of the present invention has an action (1) of mixing the raw material powder so that the raw material powder filled in the molding container does not segregate, and an action of reducing the height at which the raw material powder falls (2). Have These functions will be described in order.

(1) Action of mixing raw material powder The filling cylinder of the production method of the present invention has a feeder for supplying raw material powder at the top, and the supplied raw material powder falls inside the filling cylinder. The dropped raw material powder is once held by the barrier member inside the filling cylinder and falls from the opening at the bottom of the filling cylinder. The layer of the raw material powder once held on the barrier member inside the filling cylinder is configured such that the particles that have fallen first are deposited on the lower layer side, and the particles that have fallen late are deposited on the upper layer side. If the raw material powder is not continuously supplied, a coarse or low aspect ratio raw material powder layer and a fine or high aspect ratio raw material powder layer are formed, and segregation occurs on the barrier member. However, when the deposition of the raw material powder on the barrier member increases, the segregation formed on the barrier member is eliminated by dropping and mixing together with the raw material powder deposited so far.

(2) The action of reducing the height at which the raw material powder falls The filling cylinder of the manufacturing method of the present invention is inserted and filled from the opening of the molding container, so that the height at which the raw material powder falls is lowered. Can do.
In the raw material powder falling from the barrier member inside the filling cylinder, segregation caused by air resistance between the feeder and the barrier member is eliminated by the barrier member. The raw material powder dropped from the barrier member is filled into the filling container from below. Since the filling cylinder is inserted and filled from the opening of the molding container, the height at which the raw material powder falls inside the filling container can be lowered, and the influence of segregation due to air resistance during this period can be reduced. Can do.

  The filling apparatus of the manufacturing method of the present invention can reduce the segregation of the raw material powder filled in the filling container by the two actions described above.

  The filling device of the manufacturing method of the present invention does not need to take out a jig or the like inside the molding container and does not need to be taken out, and the raw material powder is filled from under the filling container. Does not move the powder. For this reason, a big space | gap is not produced in the raw material powder by the movement of the raw material powder inside a shaping | molding container. Since a large void is not formed, anisotropic variation or density variation does not occur in a portion where the large void is formed after molding, and it is possible to make it difficult for the molded body or the fired body to crack.

In the present invention, a large void means not a void formed in a gap where raw material powder particles are stacked, but an overwhelming void with respect to the particle size of the raw material powder. Examples of such a large gap include a gap formed when an object existing inside the filled raw material powder is removed or moved. Such voids are crushed by the pressure of the powder and become traces of oriented raw material powder particles. In particular,
(1) When the rod embedded in the filled raw material powder is pulled out, when the gap in the shape of the end surface formed at the end of the rod moves to form a linear trace,
(2) When the string moves inside the filled raw material powder and the linear void after the string passes forms a planar trace,
(3) When a force is applied to the filled raw material powder and deformed to form a void like a ground crack, it will be crushed to form a crack in the shape of a ground crack,
Etc. Since these traces form a discontinuous state with the gap as a boundary when the gap is crushed, the orientation of the raw material powder is not continuous, causing cracks in the subsequent firing process and graphitization process. Become. Further, if the large voids are not sufficiently crushed, the raw material powder becomes dense around the voids, and pressure is not sufficiently applied to the molding process, which causes variation in bulk density. If there is a variation in bulk density, distortion is likely to occur in the molding process, firing process, or graphitization process, which causes cracks due to internal stress.

  It is preferable that the filling apparatus of the manufacturing method of the present invention further includes an elevator, and the elevator raises the height of the forming container to the filling cylinder while filling the raw material powder. Since the elevator raises the height to the filling cylinder with respect to the molding container, the height of the raw material powder falling from the filling cylinder can be kept low from the start to the end of the filling, and segregation occurs after falling from the barrier member Can be suppressed.

When the elevator raises the height to the filling cylinder relative to the molding container, it means a relative height, and the elevator has a function of lowering the molding container even if it has a function of raising the filling cylinder. May be.
Moreover, the speed | rate which raises the height to the filling cylinder with respect to the shaping | molding container of an elevator can be set according to the speed | rate with which raw material powder is filled. For example, when the elevator is operated by a hydraulic cylinder, the ascending speed can be controlled by a flow control valve or the like.
The elevator may operate continuously or intermittently.

The filling device of the manufacturing method of the present invention further includes a detector that detects the amount of raw material powder filled in the molding container, and interlocks with the amount of raw material powder filled in the molding container detected by the detector. It is preferable that the elevator raises the height to the filling cylinder with respect to the molding container.
The raw material powder is filled in the molding container, and the height in the molding container is gradually increased. By providing the detector and the elevator, the distance between the raw material powder in the molded container and the filling cylinder is kept constant by the elevator in conjunction with the height information of the raw powder in the molded container emitted from the detector. Can do. By such a mechanism, the height at which the raw material powder falls from the filling cylinder can be kept small. For this reason, it is possible to prevent segregation of the raw material powder falling from the filling cylinder.

  Although the detector of the manufacturing method of the present invention is not particularly limited, a load cell, a distance meter, or the like can be used. When a load cell is used for the detector, the height of the filled raw material powder can be calculated by dividing the mass of the filled raw material powder by the moving density of the raw material powder and the area of the bottom surface of the molding container. . When a distance meter is used for the detector, the height of the filled powder can be directly measured. As the distance meter, a laser distance meter, an ultrasonic distance meter, a microwave distance meter, or the like can be used. The mechanism by which the elevator raises the height to the filling cylinder with respect to the molding container may be either a mechanism for raising the filling cylinder or a mechanism for lowering the molding container, and is not particularly limited. As the elevator, the filling cylinder has a feeder for supplying the raw material powder at the top, so that the whole configuration can be simplified by applying a mechanism for lowering the molded container.

  The barrier member of the manufacturing method of the present invention will be described. The raw material powder supplied from the feeder falls on the barrier member and is temporarily deposited by the frictional force with the barrier member surface. When the raw material powder further falls, the amount of deposition on the barrier member increases, and the inclination angle of the surface of the deposited raw material powder increases. When the inclination angle of the surface of the raw material powder exceeds the angle of repose and the raw material powder cannot be held by the frictional force with the barrier member, the raw material powder falls from the barrier member all at once. At this time, the raw material powder deposited while being segregated is mixed. The angle of repose of the raw material powder is, for example, 30 to 40 °.

The inclination angle of the upper surface of the barrier member of the production method of the present invention is preferably 20 to 60 °.
When the inclination angle of the upper surface of the barrier member of the production method of the present invention is less than 20 °, the angle of repose of the raw material powder is significantly smaller, so that the raw material powder that always accumulates on the barrier member and does not fall increases.
Furthermore, the inclination angle of the upper surface of the barrier member of the manufacturing method of the present invention is preferably 30 ° or more. When the inclination angle of the upper surface of the barrier member is 30 ° or more, it is close to the angle of repose of the raw material powder, so when the raw material powder deposited on the barrier member falls, it tends to fall together and always on the barrier member. Raw material powder that accumulates and does not fall can be reduced.

When the inclination angle of the upper surface of the barrier member of the production method of the present invention exceeds 60 °, the raw material powder is difficult to deposit on the barrier member, and the action of eliminating segregation is reduced.
Furthermore, the inclination angle of the upper surface of the barrier member of the manufacturing method of the present invention is preferably 50 ° or less. When the inclination angle of the upper surface of the barrier member is 50 ° or less, the raw material powder is easily deposited on the barrier member, and the effect of eliminating segregation can be increased.
The upper surface of the barrier member of the manufacturing method of the present invention may be flat or curved, and in the case of a curved surface, the barrier member has a portion where the inclination angle of the upper surface of the barrier member is 20 to 60 °. It only has to be. More desirably, the barrier member preferably has a portion having an inclination angle of 30 ° or more or 50 ° or less.

  As for the barrier member of the manufacturing method of this invention, it is desirable to consist of multiple. When there are a plurality of barrier members, the falling of the raw material powder from the barrier member occurs separately for each barrier member, so that the pulsation when the raw material powder falls into the molded container from the barrier member can be reduced. it can.

  The barrier member of the manufacturing method of the present invention may be fixed, or may be provided with a mechanism that vibrates, rotates, or swings. When a mechanism that vibrates, rotates, or swings is provided, the falling of the raw material powder deposited on the barrier member can be promoted, and the raw material powder adhering to the barrier member can be reduced. When a mechanism that vibrates, rotates, or swings is provided, the raw material powder can be easily dropped. The mechanism that vibrates, rotates or swings may operate constantly or at intervals. When operating at intervals, raw material powder can be deposited while not operating, and falling of the raw material powder can be promoted while operating. When operating at intervals, it is preferred that the individual barrier members operate alternately or sequentially rather than simultaneously. By operating alternately or sequentially, the pulsation of the raw material powder generated by the barrier member can be reduced and segregation can be made more difficult to occur. When the barrier member includes pores that vibrate, rotate, or swing, it is only necessary to have a time zone in which the inclination angle of the upper surface of the barrier member is 20 to 60 °. More desirably, it has a time zone in which the inclination angle of the upper surface of the barrier member is 30 ° or more or 50 ° or less.

Although the area which a barrier member projects with respect to opening of the filling cylinder of the manufacturing method of this invention is not specifically limited, It is preferable that it is 40 to 90%. When the area where the barrier member is projected is 40% or more, the raw material powder falling from the feeder easily accumulates on the barrier member and is temporarily retained, absorbs the pulsation of the raw material powder from the feeder, and generates segregation. Can be easily reduced. When the area projected by the barrier member is 90% or less, a sufficient path can be secured for the raw material powder falling from the feeder to fall within the filling cylinder, so that the filling can be performed smoothly without blocking. it can. When there are a plurality of barrier members, the area where the barrier members are projected onto the opening of the filling cylinder is an area where all of the plurality of barrier members are simultaneously projected.

<Molding process>
In the molding step of the production method of the present invention, the raw material powder filled in the molding container in the filling step is molded by applying a hydrostatic pressure to obtain a molded body.
In the molding step, the molding container can be put into a CIP molding apparatus that is pressurized by a pressure medium such as water in the pressure container.
In the molding container of the manufacturing method of the present invention, the raw material powder filled in the molding container is sealed by being covered with a lid so that the pressure medium does not enter in the CIP molding apparatus.

The molding pressure in the production method of the present invention is not particularly limited. For example, the raw material powder is molded by pressurizing at 10 to 500 MPa to form a molded body. When the molding pressure is 10 MPa or more, a compact with a high bulk density is obtained, and a dense graphite material can be obtained. In addition, a molded body having a sufficiently high bulk density can be obtained before the molding pressure reaches 500 MPa. During the firing of the molded body, the decomposition gas of the binder component escapes from the pores to promote carbonization. Even when the molding pressure exceeds 500 MPa, the binder component of the molded body decomposes while softening and forms pores, so that the bulk density is hardly increased, and the bulk density of the obtained graphite material increases even when the molding pressure exceeds 500 MPa. It will be difficult.
The molding container to which pressure is applied by the CIP molding apparatus is taken out of the CIP molding apparatus and then opened. A molded body is taken out from the opened molded container.
Since the CIP molding apparatus isotropically pressurizes using a liquid pressure medium, there is a feature that the anisotropic ratio of the characteristics of the graphite material can be reduced.

<Baking process>
In the firing step of the production method of the present invention, the fired body is obtained by firing the molded body and carbonizing the pitch as the binder.
The subsequent graphitization step is also a similar heating step, but the firing step is slowly heated to remove volatiles, and the graphitization step is heated at a high temperature to accelerate the crystallization of graphite. To do. Since the energy density for heating the molded body in the firing step and the energy density for heating the fired body in the graphitization step are greatly different, each is generally heated in a dedicated furnace. In the firing step, the molded body may be carbonized and heated until a fired body is obtained. Therefore, heat sources such as heating by combustion and heating by electricity are not particularly limited, and heating by combustion with low energy density can also be applied. On the other hand, since the subsequent graphitization process needs to be heated to a high temperature, it is heated using electricity. Heating by combustion with low energy density is not suitable for graphitization because energy is discarded by warm exhaust gas and a high temperature cannot be obtained.

  The firing step of the production method of the present invention can be used in any furnace using a heating element. It is not particularly limited such as a combustion furnace or an electric furnace. When using a combustion furnace, the fuel is not particularly limited, and any of natural gas, propane gas, carbon monoxide, heavy oil, and the like can be used.

  The firing temperature in the firing step of the production method of the present invention is not particularly limited, but is preferably 700 to 1500 ° C. When the firing temperature is 700 ° C. or higher, the volatile matter is sufficiently removed from the molded body, so that carbonization proceeds, pores are formed and decomposition gas is easily released, and the thermal conductivity of the fired body is increased. Even if heated rapidly in the graphitization step, it can be made difficult to crack. When the firing temperature exceeds 1500 ° C., energy loss increases. The reason will be described below. The fired body having a firing temperature of 1500 ° C. or less has a sufficient amount of volatile matter and has pores formed therein, so that the decomposition gas is sufficiently easily removed in the graphitization step, and the carbonization proceeds sufficiently. The fired body has a sufficiently high thermal conductivity. When firing at a temperature exceeding 1500 ° C., the ease of gas removal and the change in thermal conductivity of the fired body with respect to the temperature are small. The effect of making it easy to bake becomes small, and even if it heats exceeding 1500 degreeC, it will be the loss of that energy.

The firing step of the production method of the present invention can be fired in any atmosphere as long as the molded body is not oxidized. The firing atmosphere may be any atmosphere such as a vacuum, a reducing atmosphere, or an inert gas atmosphere. Examples of the reducing atmosphere include hydrocarbon gas, carbon monoxide, and hydrogen. Examples of the inert gas atmosphere include nitrogen and argon.
The rate of temperature increase in the firing step of the production method of the present invention is not particularly limited. In order to reduce the temperature difference between the surface and the inside and make it difficult to crack as the size of the molded body increases, it is desirable to fire slowly. For example, in the case of a molded body having a thickness of 400 mm, it can be fired at 0.2 to 4 ° C./hr.

The fired body that has reached the maximum temperature is preferably allowed to cool while maintaining the atmosphere in a vacuum, reducing atmosphere, or inert gas atmosphere, and is preferably taken out after cooling.
In this specification, the firing temperature is the highest processing temperature in the firing step.

<Graphitization process>
In the graphitization step of the production method of the present invention, the fired body carbonized in the firing step is heated and graphitized.
The graphitization step of the production method of the present invention may be graphitized using any graphitization furnace. For example, an Acheson furnace or an induction furnace can be used. In such a graphitization furnace, the periphery is surrounded by a heat insulating material, and a fired body is packed and heated in the center. It can also be graphitized in a muffle furnace using a resistance heater. Examples of resistance heaters include graphite heating elements and tungsten heating elements.

  Most of the volatile matter is removed from the carbonized fired body, and almost no decomposition gas is emitted even when heated. For this reason, it can graphitize, without tar etc. adhering to the heat insulating material surrounding a fired body. When a fired body or molded body having a low firing temperature is heated in a graphitization furnace, a cracked gas having a large molecular weight is generated and becomes tar and adheres to a heat insulating material and carbonizes. Since the tar carbide adhering to the heat insulating material bonds the heat insulating materials, the heat insulating property is deteriorated.

  The graphitization temperature in the graphitization step of the production method of the present invention is not particularly limited, but is desirably 2000 ° C. or higher. When the graphitization temperature is 2000 ° C. or higher, the carbon constituting the fired body is sufficiently crystallized, and a graphite material having processability, conductivity, and heat conductivity can be obtained. When the graphitization temperature is less than 2000 ° C., a carbonaceous material is obtained, which is hard and has low thermal conductivity and low conductivity. The graphitization temperature in the graphitization step of the production method of the present invention is not particularly limited, but is preferably 3500 ° C. or lower. Since the sublimation temperature of graphite is about 3650 ° C., when the graphitization temperature is 3500 ° C. or less, the vapor pressure of graphite on which graphitization is performed can be kept low. For this reason, there is little graphite sublimated from the surface of the fired body in which graphitization has progressed in the graphitization furnace, and alteration of the surface of the graphite material can be reduced.

Although the temperature increase rate of graphitization is not particularly limited, for example, the temperature can be increased at 10 to 100 ° C./hr at 1000 ° C. or less where the crystallization of the fired body has not progressed. The temperature can be raised at, for example, 30 to 200 ° C./hr at a temperature exceeding 1000 ° C. at which the crystallization of the fired body starts to proceed.
In this specification, the graphitization temperature is the highest processing temperature in the graphitization step.

  Embodiments 1 and 2 of a specific method for producing a graphite material according to the present invention will be described below with reference to the drawings.

FIG. 2 is an explanatory view showing the filling device according to the first embodiment of the method for producing a graphite material of the present invention.
The raw material powder 1 is filled in the upper tank 8 and guided to the upper part of the filling cylinder 3 by the feeder 4. When the feeder rotates, the raw material powder falls from the upper part of the filling cylinder 3 into the filling cylinder 3 and is temporarily held by the barrier member 5 arranged inside the filling cylinder 3, and then into the molding container 2. Fall. At this time, the barrier member 5 acts so as to eliminate segregation of the raw material powder, and since the filling cylinder 3 is inserted into the molding container 5, the raw material powder falling from the filling cylinder is hardly separated by the action of air. Segregation can be made difficult to occur.
The barrier member is composed of four flat bars, and the inclination angle of the upper surface is 45 °.

  A detector 7 attached to the side surface of the filling cylinder 3 detects the distance between the raw material powder 1 filled in the molding container 2 and the filling cylinder 3, and the raw material powder 1 filled in the lower end of the filling cylinder 3 and the molding container 2. The filling cylinder 3 is raised by the elevator 6 so as to keep the interval between the upper ends of the cylinders constant. At this time, the feeder 4 and the tank 8 connected to the filling cylinder 3 are also raised at the same time. The detector is an ultrasonic distance meter, and controls the elevator so that the distance from the lower end of the filling cylinder to the top of the filled raw material powder is kept constant.

  FIG. 3 is an explanatory view showing a filling apparatus according to Embodiment 2 of the method for producing a graphite material of the present invention. Embodiment 2 differs in the structure of the filling apparatus of Embodiment 1, the detector 7, and the elevator 6, and the other part is the same structure. The detector according to the second embodiment is a scale for weighing the molded container 2, and the elevator 6 can move the molded container 2 side up and down instead of the filling cylinder 3 side. The elevator 6 can lower the molding container 2 according to the mass of the raw material powder measured by the detector, and keeps the distance from the lower end of the filling cylinder 3 to the top of the raw material powder filled in the molding container 2 constant. The elevator 6 is controlled as follows.

  FIG. 5 is an explanatory view showing a state in which raw material powder is deposited on the barrier member 5 of the graphite material manufacturing method of the present invention and falls. (A) shows the barrier member in a state where nothing is placed. The size is, for example, a flat bar having a width of 100 mm and a thickness of 12 mm, and the inclination angle is 45 °, which is larger than the repose angle of the raw material powder. The size, shape, quantity, and inclination angle are not particularly limited. (B) shows the state in which the raw material powder 1 has fallen from the upper part of the filling cylinder and has started to accumulate on the upper surface of the barrier member. At the lower end of the barrier member, the raw material powder immediately falls, but at other portions, the raw material powder is held by the frictional force with the surface of the barrier member. (C) shows a state in which the raw material powder is further accumulated. If the raw material powder accumulates more than this, it cannot be held by the frictional force with the surface of the barrier member and becomes broken. In (d), since the raw material powder 1 further accumulates and the raw material powder cannot be held by the frictional force with the barrier member surface, and the inclination angle of the surface of the deposited raw material powder exceeds the angle of repose, the raw material powder becomes a barrier. A mode that it falls from the lower end of a member at a stretch is shown. At this time, the raw material powder is dropped and mixed together with the raw material powder deposited so far. Since the order of the falling powder falls from the side close to the lower end of the barrier member, it does not fall in the order in which it falls from the feeder. For this reason, the raw material powder segregation caused by the pulsation of the feeder, the start and stop of the filling is eliminated by the barrier member.

  FIG. 6 shows a modification of the barrier member of the method for producing a graphite material of the present invention. Both are sectional views when viewed from the side of the filling cylinder. (A) is one barrier member, (b) is five barrier members arranged in the horizontal direction and inclined in the same direction, (c) is five barrier members arranged in the horizontal direction. Are inclined in different directions, (d) further includes four barrier members arranged in the horizontal direction so as to alternate with the upper portions of the five barrier members arranged in the horizontal direction. (E) shows that the five barrier members arranged in the horizontal direction vibrate, and (f) shows that the five barrier members arranged in the horizontal direction rotate around the longitudinal direction. This is the case.

  The barrier member of the present invention can be used in combination with the barrier members described in (a) to (f). Specifically, the number of barrier members, the angle of inclination, the number of steps in the vertical direction, the presence or absence of vibration, the period of vibration, the amplitude of vibration, the presence or absence of rotation, the number of revolutions, the presence or absence of rocking, the period of rocking, rocking There are no particular restrictions on the combination of these angles, etc., and any combination can be applied as appropriate.

  Below, it describes in order of an Example and a comparative example about the manufacturing method of this invention.

<Filling process>
The following are used as raw material powder. The coal-based coke pulverized to a median diameter of 15 μm and a kneader heated with a tar pitch are kneaded, and the obtained kneaded product is pulverized to obtain a raw material powder having a median diameter of 25 μm.
Prepare a molding container to be filled with raw material powder. The molded container can be covered and sealed with a lid. The inner dimension of the molded container has a rectangular parallelepiped cavity of 400 × 600 × 1800 (height) mm. Both the molded container and the lid are made of rubber.

FIG. 4 is an explanatory view showing a filling device used in Example 1 of the method for producing a graphite material of the present invention.
The raw material powder is filled into the forming container 2 using the filling device 10 shown in FIG. 4 described below. The filling device 10 has a tank 8 for storing raw material powder in the upper part, and is supplied to the upper part of the filling cylinder 3 by a feeder 4 made of a screw. The raw material powder 1 that has reached the top of the filling cylinder 3 falls into the filling cylinder 3. The thickness of the filling cylinder 3 is φ250, and a hood having an opening with a lower end 250 × 400 is attached. In the filling cylinder 3, three barrier members 5 made of a flat bar having a width of 60 mm are provided so that the inclination becomes 30 °.

The filling cylinder 3 is inserted from the opening of the molding container 2 to the back. The forming container 2 has an elevator 6 that descends at a constant speed. By this mechanism, the height of the filling cylinder 3 with respect to the molding container 2 can be raised while being kept substantially constant.
For filling the raw material powder, the feeder 4 is rotated to drop the raw material powder from the upper part of the filling cylinder 3 and at the same time the filling container is slowly lowered by the elevator 6. By slowly lowering the filling container, the height of the filling container up to the filling cylinder is slowly raised, and the raw material powder is filled up to the upper end of the forming container. During the filling, a bridging phenomenon easily occurs in the storage tank due to the characteristics of the raw material powder, and the raw material powder is dropped intermittently from the feeder.

<Molding process>
Cover the molded container filled with the raw material powder in the filling step and seal it with a rubber band. The filled container is carried into the CIP molding apparatus and pressurized by press-fitting a liquid pressure medium into the CIP molding apparatus. The CIP molding apparatus applies a pressure of 100 MPa and pressurizes. After pressurization, the pressure is reduced by gradually removing the pressurization medium, and after the pressure reduction, the molding container is taken out from the CIP molding apparatus.
The lid is removed from the carried-out molded container, and the molded body formed with the raw material powder is taken out from the molded container.

<Baking process>
The molded body obtained in the molding step is packed in a stainless steel firing can and covered with a stainless steel lid. The fired can with lid is packed in a gas furnace and fired. The molded body packed in the calcined can is heated to 900 ° C. at a heating rate of 1.5 ° C./hr. After cooling, the calcined can is removed from the gas furnace. In the fired can, the molded body is fired to form a fired body.

<Graphitization process>
The fired body obtained in the firing process is packed in an Acheson furnace whose wall surface is covered with a heat insulating material, covered with covering powder made of artificial graphite from above, and filled between the upper part of the fired body and the fired body. To do. An electric current is passed from the graphite electrodes at both ends of the Acheson furnace so as to pass through the fired body and the granular material between the fired bodies to generate heat by resistance and graphitize. The current for heating is switched according to the temperature range of the fired body, heated up to 1200 ° C. with a current of about 15 ° C./hr, and up to 2500 ° C. with a current of about 30 ° C./hr. Heat. If the temperature exceeds 1200 ° C, the thermal shrinkage of the fired body will be reduced and it will be difficult to crack even if the heating rate is increased, so that it will resist heat dissipation from the Acheson furnace and reach the maximum temperature (graphitization temperature) quickly. The amount of heat to be heated is made large enough to make full use of the power capacity of the power and graphitized.

  After reaching the graphitization temperature, the power supply is stopped and the heat is dissipated naturally. Gradually remove the powder from the top that has been cooled by natural heat dissipation. A graphite material obtained by graphitizing the fired body is obtained inside the Acheson furnace. The upper surface of the graphite material is exposed when it is gradually removed from the upper filling powder cooled by natural heat dissipation. The graphite material with the upper surface exposed can be taken out by tongs.

  The graphite material produced according to Example 1 did not generate cracks in any of the molding process, firing process, and graphitization process.

(Comparative Example 1)
In order to form a graphite material having a different filling process, the manufacturing process proceeds according to the manufacturing process of Example 1 except for the filling process.

<Filling process>
The same raw material powder as in Example 1 is filled in the same molding container. Filling is supplied from a storage tank by a feeder, and the raw material powder dropped from the feeder is directly put into a forming container. When the raw material powder falls from the feeder, fine dust of the raw material powder floats and slowly settles while receiving air resistance. On the way, the bridging phenomenon of the raw material powder occurs in the storage tank, and the raw material powder is dropped intermittently from the feeder. While the supply of the raw material powder from the feeder is stopped due to the bridging phenomenon of the storage tank, the dust of the floating raw material powder settles in the molding container, and a layer of the raw material powder having a fine particle diameter is formed.

<Molding process>
Similar to the molding step of Example 1, a molded body is obtained using a CIP molding apparatus.

<Baking process>
In the same manner as in the firing step of Example 1, it is packed in a firing can and fired using a gas furnace to obtain a fired body.

<Graphitization process>
In the same manner as in the graphitization step of Example 1, the Acheson furnace is packed and energized to obtain a graphite material.

  The graphite material produced according to Comparative Example 1 cracked during the firing stage. Cracks occurred in the fired body along the horizontal direction of the filling process. It is considered that the position of the crack corresponds to the raw material powder layer having a fine particle diameter formed at the time of filling.

(Comparative Example 2)
A graphite material is produced in the same manner as in Comparative Example 1. In Comparative Example 2, in order to prevent the occurrence of cracks, the difference from Comparative Example 1 is that the segregation breaking operation is performed to break the layer of the raw material powder having a fine particle diameter formed on the raw material powder in the molding container after filling. It is.
Below, the manufacturing method of the comparative example 2 and the segregation fracture operation in a filling process are concretely demonstrated.

<Filling process>
The same raw material powder as in Example 1 is filled in the same molding container. A 400 × 600 mm grid-like jig formed of a φ16 mm iron round bar is submerged in the bottom of the molding container. The size of the lattice of the lattice-shaped jig is 100 mm on one side.

The filling is supplied from the storage tank by a feeder, and the raw material powder dropped from the feeder is directly put into the molding container. When the raw material powder falls from the feeder, fine dust of the raw material powder floats and slowly settles while receiving air resistance. On the way, bridging of the raw material powder easily occurs in the storage tank, and the raw material powder is dropped intermittently from the feeder. While the supply of the raw material powder from the feeder is stopped due to the bridging phenomenon of the storage tank, the dust of the floating raw material powder settles in the molding container, and a layer of the raw material powder having a fine particle diameter is formed.
Next, a segregation fracture operation is performed. Specifically, after filling, the lattice-shaped jig is pulled up from the bottom of the forming container to destroy the layer of the raw material powder having a fine particle diameter formed in the forming container.

<Molding process>
Similar to the molding step of Example 1, a molded body is obtained using a CIP molding apparatus.

<Baking process>
In the same manner as in the firing step of Example 1, it is packed in a firing can and fired using a gas furnace to obtain a fired body.

<Graphitization process>
In the same manner as in the graphitization step of Example 1, the Acheson furnace is packed and energized to obtain a graphite material.

  The graphite material produced according to Comparative Example 2 cracked during the firing stage. Lattice-shaped cracks were formed on the upper surface when the fired body was filled. After filling, it was possible to break the layer of raw material powder with a fine particle diameter by pulling up the lattice-shaped jig that had been submerged in the bottom of the molding container. It is considered that the raw material powder having a high aspect ratio rearranged and the defect having weak strength was formed.

  In Example 1, the filling apparatus of the present invention is used in which a filling cylinder having a feeder for supplying raw material powder at the top and a barrier member for receiving the raw material powder is inserted into the inside of the molding container and filled with the raw material powder. . For this reason, even if pulsation occurs in the raw material powder supplied from the feeder, the raw material powder is once held by the barrier member inside the filling cylinder, and when the fixed amount is accumulated, the held raw material powder falls together. Can absorb the pulsation of raw material powder.

Further, since the filling cylinder is inserted into the molding container, the distance from the barrier member inside the filling cylinder to the dropping into the molding container can be shortened. For this reason, it was confirmed that the segregation caused by the difference in the dropping speed due to the air resistance of the raw material powder falling from the filling cylinder can be minimized and the occurrence of cracks due to the segregation can be prevented.
On the other hand, in Comparative Example 1, the raw material powder is dropped directly from the feeder into the forming container. For this reason, it was confirmed that the pulsation of the raw material powder supplied from the feeder could not be absorbed, segregation occurred, and cracks due to segregation occurred.
Further, in Comparative Example 2, since the lattice-shaped jig was submerged inside the molded container and then filled, and taken out after filling, anisotropy was caused in the raw material powder when taken out, causing cracks. It was confirmed that

DESCRIPTION OF SYMBOLS 1 Raw material powder 2 Molding container 3 Filling cylinder 4 Feeder 5 Barrier member 6 Elevator 7 Detector 8 Tank 10 Filling device

Claims (5)

A filling step of filling a molding container with raw material powder obtained by kneading and pulverizing coke and pitch, a molding step of applying a hydrostatic pressure to the molding container to obtain a molded body, and firing the molded body to obtain a fired body In a method for producing a graphite material comprising a firing step and a graphitization step of graphitizing the fired body to obtain a graphite material,
The filling step is a filling device that inserts a cylindrical filling cylinder having a feeder for supplying the raw material powder at an upper portion thereof and a barrier member for temporarily holding the raw material powder therein, and is filled with the raw material powder. A method for producing a graphite material, which is characterized by comprising:   2. The method for producing a graphite material according to claim 1, wherein the filling device further includes an elevator, and the elevator raises the height of the forming container to the filling cylinder while filling the raw material powder. 3. .   The filling device further includes a detector that detects the amount of raw material powder filled in the molding container, and the elevator moves in conjunction with the amount of raw material powder filled in the molding container detected by the detector. 3. The method for producing a graphite material according to claim 2, wherein the height of the molded container is raised so as to keep the height to the filling cylinder constant.   The method for producing a graphite material according to any one of claims 1 to 3, wherein an inclination angle of an upper surface of the barrier member is 20 to 60 °.   The said barrier member consists of two or more, The manufacturing method of the graphite material as described in any one of Claims 1-4 characterized by the above-mentioned.

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