JP2010241129A - Method of producing powder compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a powder compact, that excels in mold releasability, suppresses product variance, and improves dimensional accuracy and increases productivity and, particularly is optimally applicable to a method of producing a compact for a turbine. <P>SOLUTION: In the method of producing a powder compact, a powder compact is produced by casting a slurry containing ceramic and/or metallic powder, a dispersion medium, and a gelling agent and by solidifying it by gelling the slurry. After the slurry is cast in a mold 3 for a powder compacting and hardened, the hardened slurry is cooled with the mold in which the powder compact 1 is stored while it is hardened. Thus, by causing temperature difference in the mold 3 and the powder compact 1, mold releasing is performed. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a molded body from ceramic and / or metal raw powders. More specifically, the present invention relates to a method for producing a powder molded body in which a slurry containing a gelling agent is cast and cured by gelling the slurry to obtain a molded body.

  Conventionally, methods such as press molding, cast molding, and injection molding have been used as methods for producing molded bodies from ceramic and metal raw material powders, but it is difficult to mold complex shapes and dimensional accuracy is low. Since thick-walled products are prone to cracking and difficult to densify the molded product, the so-called gel casting method has recently attracted attention as a method that can solve these problems.

  In the gel casting method, a slurry containing a raw material powder of ceramic, metal, etc., a dispersion medium, and a gelling agent is injected into a mold, and then the slurry is gelled by addition of a temperature condition or a crosslinking agent. It is a manufacturing method for powder molded bodies and the like to obtain a molded body by curing, and since the slurry can be cast with high fluidity before gelation, it is easy to mold complex shaped products, and after casting Can obtain a molded article having sufficient strength to withstand handling by gelation.

  Conventionally, as this gel casting method, a raw material powder such as ceramic and metal and a gelling agent mainly composed of a prepolymer such as polyvinyl alcohol, epoxy resin, and phenol resin are dispersed in a dispersion medium to form a slurry. After the prepared slurry was poured into a metal mold, a crosslinking agent was further added, and the slurry was cured by crosslinking reaction between the crosslinking agent and the gelling agent. A method is known in which a molded body is obtained by removing the sheet.

By the way, in this gel casting method, a mold release process is performed after casting and hardening a slurry conventionally.

  In the case of a three-dimensional complicated shape product, if a large amount of a cross-linking agent and a gelling agent are added to increase the strength of the molded product after curing, the molded product will crack due to interference with the mold due to volume change during curing. On the other hand, if the amount of the crosslinking agent and the gelling agent is decreased so as to suppress the volume change at the time of curing, the strength of the molded body after curing is low, and the molded body is broken due to the friction between the mold and the molded body at the time of release. In such a case, after the slurry is cast and cured, the powder compact is heated, and the compact and the compact are dried and shrunk so that the compact does not shrink and interfere with the mold and break. A mold release process is performed to release the powder compact from the mold after forming a minute clearance between the two and increasing the strength of the compact. In such a drying process by heating, (1) when the powder molded body is dried, the powder molded body (before drying) is constrained in the mold for the molded body, so that the area that comes into contact with the outside air is reduced. The problem is that the progress of drying becomes non-uniform and the difference in shrinkage of the powder compact during drying becomes large within the same compact. (2) Further, the powder compact is constrained and contracted by the mold for the powder compact. Therefore, there is a problem that defects such as cracks are likely to occur.

  Furthermore, during the mold release process for releasing the powder compact from the mold, (3) there is a problem that the frictional force between the mold and the compact is greatly cracked. (4) In order to suppress the state in which the progress of drying is uneven and the state in which the drying is constrained and contracted by the mold for the powder molded body, slow drying at a low temperature is necessary and takes time. (5) The shrinkage that creates the clearance between the mold and the molded body is minimal, there is no cracking, and the dry region has a strength that prevents the molded body from being broken by the friction between the mold and the molded body at the time of mold release, and is difficult to control. Therefore, in the powder molded body manufactured by the conventional gel casting method, the powder molded body is cracked or broken (particularly at the time of mold release) due to the above-mentioned complex problems, and the product It was inferior in variation and dimensional accuracy.

  Furthermore, in recent years, the shape of the molded body has become complicated, which has spurred the above-mentioned problems. For example, in the case of molding a fine complex shape, when the mold is released, the fine shape of the molded body is easily damaged, and in the case of manufacturing a powder molded body having a shape such as an undercut When a molding die such as an undercut shape is used, there is a problem that the shape of the molded body is not damaged but cannot be released.

  In particular, when manufacturing a complicated shape product such as a turbine with a shaft among them, the shape is fine and complicated, and therefore, in the mold release process, there is a problem that an extremely thin part (for example, a blade) is broken. There is a problem that it is easy. In the conventional manufacturing method, since it is difficult to control drying shrinkage, it is difficult to prevent breakage and malfunction. In addition, although measures such as drying for a long time in order to reduce breakage and malfunctions are taken, it is not sufficient, causing a vicious cycle of reduced production efficiency. On the other hand, when trying to release the mold without drying shrinkage, since the solvent remains in the powder molded body, there is no clearance between the molded body and the molded body frame where the molded body strength is insufficient. Will become larger and the wings will be damaged. Therefore, sufficient measures have not been taken and further improvements are desired.

  There exists the following patent document 1 with respect to such a subject.

  One or more types selected from ceramic, glass, or metal for the purpose of curing the slurry without adding a large amount of resins and producing a powder compact without requiring strict temperature control during the curing operation. The slurry is cured by adding a reactive substance that loses or lowers the dispersing ability of the dispersing agent due to the interaction with the dispersing agent to the slurry prepared by dispersing the powder in the dispersing medium using the dispersing agent. And a method for producing a powder compact is disclosed.

Japanese Patent Laid-Open No. 11-048222

  However, in the literature 1, after performing casting (filling) of a slurry as a powder raw material, heating is performed to perform a drying process. Shrinkage due to drying may occur. In addition, the shrinkage difference tends to be non-uniform, and it is difficult to set drying conditions that make the drying shrinkage difference uniform. For this reason, product variations are likely to occur. Therefore, further improvements are required.

  The present invention has been made in order to solve such problems, and the slurry is poured into a mold for a powder molded body and cured, and then the cured powder molded body is stored. By cooling the molds and releasing them to produce powder compacts, the powder compacts have excellent releasability, can suppress product variations, improve dimensional accuracy, and improve productivity. A manufacturing method is provided. In particular, it can be suitably used for producing a molded article for a turbine with a shaft.

[1] Manufacture of a powder molded body obtained by casting a slurry containing ceramic and / or metal powder, a dispersion medium, and a gelling agent, and solidifying the slurry by gelling. In this method, the slurry is poured into a mold for a powder compact, and then cooled together with the mold containing the powder compact while being cured, so that a temperature difference is generated between the mold and the powder compact. A method for producing a powder molded body, wherein the powder molded body is produced by performing mold release treatment.

[2] Further, the cooled powder molded body is subjected to mold release treatment by causing a temperature difference between the mold and the powder molded body together with the housed mold at room temperature, thereby producing the powder molded body [1] ] The manufacturing method of the powder molded object of description.

[3] The powder molded body according to [1] or [2], wherein during the cooling, the residual solvent remaining in the powder molded body is condensed on the surface of the mold to produce the powder molded body. Manufacturing method.

[4] The powder molded body is manufactured using a mold having a smaller thermal conductivity and / or heat capacity than the casting slurry containing the residual solvent. [1] to [3] The manufacturing method of the powder compact in any one.

[5] The method for producing a powder molded body according to [4], wherein the mold has a thermal conductivity of 0.5 W / mK or less.

[6] The method for producing a powder molded body according to [4], wherein the mold has a heat capacity of 3 MJ / m ³ K or less.

[7] The method for producing a powder molded body according to any one of [1] to [6], wherein the powder molded body is produced using a mold made of polytetrafluoroethylene.

[8] The cooling temperature of the powder molded body is 10 ° C. or less with respect to room temperature, and the powder molded body and the powder molding mold containing the powder molded body are contained during the cooling. The method for producing a powder molded body according to any one of [1] to [7], wherein the powder molded body is manufactured by generating a temperature difference between the two and performing mold release treatment.

[9] The method for producing a powder molded body according to any one of [1] to [8], wherein the cooling time of the powder molded body is at least 30 minutes or longer.

[10] The powder molded body according to any one of [1] to [9], wherein the powder molded body is cooled for at least 30 minutes or more and then allowed to stand at room temperature for 10 minutes or longer to produce a powder molded body. Manufacturing method.

[11] The method for producing a powder molded body according to any one of [1] to [10], wherein the powder molded body is a molded body for a turbine with a shaft.

  According to the method for producing a powder molded body according to the present invention, it is possible to obtain excellent effects such as excellent releasability, suppression of product variation, improvement of dimensional accuracy, and improvement of productivity. In particular, it can be suitably used for producing a molded article for a turbine with a shaft.

It is one Embodiment of the manufacturing method of the powder compact | molding | casting which concerns on this invention, Comprising: It is a flowchart which shows the process process. 1 is an embodiment of a method for producing a powder molded body according to the present invention, and is a diagram schematically showing a cross section of a powder molded body and a powder molded body mold. FIG. 1 is an exploded perspective view schematically showing a powder compact, which is an embodiment of a method for producing a powder compact according to the present invention. FIG. 3 is a perspective view schematically showing the powder molded body and the mold for powder molded body shown in FIG. 2. 1 is a plan view schematically showing a lower mold, which is an embodiment of a method for producing a powder molded body according to the present invention. 1 is a plan view schematically showing a state in which an airfoil is set in a lower mold, which is an embodiment of a method for producing a powder molded body according to the present invention. FIG. 6B is a perspective view schematically showing the airfoil of FIG. 6A. 1 is a plan view schematically showing an upper mold for a powder molded body main body, which is an embodiment of a method for producing a powder molded body according to the present invention, and is a mold for a powder molded body main body. It is the perspective view which showed typically the upper mold | type for powder molded object main bodies of FIG. 7A. It is the perspective view which showed the fixing pin typically. FIG. 2 is a cross-sectional view schematically showing a part of the powder molded body and the state of a mold release treatment process of the powder molded body, which is an embodiment of the method for producing a powder molded body according to the present invention.

  Hereinafter, the form for implementing the manufacturing method of the powder compact of this invention is demonstrated concretely. However, the present invention broadly encompasses a method for producing a powder compact having the invention-specific matters, and is not limited to the following embodiments.

[1] Method for producing powder molded body of the present invention:
The method for producing a powder molded body of the present invention is a method in which a slurry containing ceramic and / or metal powder, a dispersion medium, and a gelling agent is cast and solidified by gelling the slurry. A method for producing a powder molded body for obtaining a body, wherein the slurry is poured into a mold for the powder molded body and then cooled together with the mold containing the powder molded body while being cured, And a powder molded body, a temperature difference is generated between the powder molded body and a mold release treatment to produce the powder molded body.

[1-1] Process of processing powder compact:
In the method for producing a powder molded body of the present invention, the adjusted desired slurry is poured into the mold for the powder molded body, and then cooled together with the mold containing the powder molded body while being cured, It is desirable to produce the powder compact by producing a temperature difference between the mold and the powder compact and releasing the mold. In this way, the slurry is poured into a mold for the powder molded body and cured, and then the mold containing the cured powder molded body is cooled to produce a temperature difference between the mold and the powder molded body. By performing the mold release process, the mold release process can be easily performed, so that it is possible to prevent tearing at the time of mold release without being influenced by the thickness or complicated shape of the powder molded body.

  That is, in the present invention, by the configuration as described above, the mold in which the powder molded body is housed is cooled to release the mold without heating and drying. In other words, after the powder molded body is cured, the powder molded body is not heated and dried, so that the shrinkage of the powder molded body does not occur in the same molded body before release, Furthermore, since the solvent in the molded body remains between the mold for the molded body / molded body, the frictional force generated between the mold and the molded body can be suppressed, and the mold release treatment can be performed without any trouble. Cracks and tears can be prevented. Therefore, it is excellent in releasability, can suppress product variation, and can improve dimensional accuracy. In addition, the drying time can be shortened and the productivity can be improved.

  Preferably, further, the cooled powder molded body is subjected to a mold release treatment by causing a temperature difference between the mold and the powder molded body together with the housed mold at room temperature, and a powder molded body is manufactured. Preferably, the cooled powder molded body is allowed to stand at room temperature together with the housed mold, and a mold difference is generated between the mold and the powder molded body so as to produce a powder molded body. Thus, by manufacturing the powder molded body, the shrinkage of the powder molded body before release can be easily controlled in the same molded body, and further, the molded body remaining between the molded body mold / molded body. This solvent makes it easy to sufficiently suppress the friction generated between the mold and the molded body, and it is possible to more reliably perform the mold release process without any defects.

  Here, in this embodiment, as shown in FIG. 1, (S1) slurry preparation processing step, (S2) slurry casting (filling) processing step, (S3) curing and cooling processing step, (S4) mold release The powder molded body is manufactured through each of the processing steps (1), (S5) drying processing step (1), (S6) mold release processing step (2), and (S7) drying processing step (2). ((S8) Completion of powder compact).

[1-1-1] Slurry preparation process:
In the production method of the present embodiment, it is desirable to use a slurry prepared from each material including ceramic and / or metal powder, a dispersion medium, and a gelling agent. This is because the effect of the present invention is easily achieved in terms of releasability and the like in addition to easy molding of the powder compact. This slurry preparation processing step is a processing step performed at the beginning of the manufacturing method of the present embodiment, as shown in (S1) of FIG. Specifically, it is preferable that a desired slurry is prepared as described below.

  As the raw material powder made of ceramic and / or metal, for example, ceramic powder such as glass, alumina, silicon nitride, silicon carbide, aluminum nitride, zirconia, or sialon, or various metal powders are appropriately used alone. Or what was used combining 2 or more types can be mentioned. In addition, the particle diameter of these raw material powders is not particularly limited as long as the slurry can be prepared, and may be set to a preferable particle diameter as appropriate according to the molded body to be manufactured.

  Further, if necessary, a dispersion medium containing an organic compound having a reactive functional group and an organic compound having a reactive functional group may be contained. For example, the organic dispersion medium includes an organic compound having a reactive functional group and capable of reacting with a gelling agent described later. Thereby, high reaction efficiency can be achieved, and it becomes possible to use a slurry having low viscosity and high fluidity while containing a component contributing to curing at a high concentration.

  Here, the above-mentioned “reactive functional group” means an atomic group that can chemically react with other components, and is formed by, for example, an ester bond described later in addition to a hydroxyl group, a carboxyl group, an amino group, or the like. It means a substance containing a carbonyl group or the like.

  As the dispersion medium, for example, among organic compounds having a reactive functional group, esters that are low-viscosity liquid substances having a viscosity at 20 ° C. of 20 cps or less, particularly esters having a total carbon number of 20 or less. And so on. Although esters are relatively stable, the overall reactivity can be enhanced by using a highly reactive gelling agent.

  Moreover, as an organic compound which comprises a dispersion medium, you may contain what has at least 1 reactive functional group, and in order to achieve higher reaction efficiency and to obtain sufficient hardening state, two or more An organic compound having a reactive functional group may be used.

  In addition, the content regarding the material in this process is described in Unexamined-Japanese-Patent No. 11-048222 of the said patent document 1, Unexamined-Japanese-Patent No. 2001-335371, and international publication 2002/085590 pamphlet.

  However, if the slurry concentration (volume% of the raw material powder with respect to the total volume of the slurry) is too low, the density of the molded body will decrease, causing problems such as reduced strength of the molded body, cracking or deformation during drying / firing. Therefore, the slurry concentration is preferably 25 to 75% by volume, more preferably 35 to 75% by volume. The viscosity of the slurry can be adjusted by the kind of the raw material powder, the amount of the dispersant, and the slurry concentration in addition to the viscosity of the reactive dispersion medium and the gelling agent described above.

  Further, the slurry in the present invention includes, for example, a catalyst for promoting the reaction between the dispersion medium and the gelling agent, a dispersant for facilitating slurry preparation, and an antifoam, as long as the effects of the present invention are not impaired. Various additives such as an agent, a surfactant, or a sintering aid for improving the properties of the sintered body can be added.

  For example, in order to improve the strength of the molded product after curing, it is preferable to add a dispersant such as a polycarboxylic acid ester.

[1-1-2] Slurry casting (filling) treatment process:
Next, the (S2) slurry casting (filling) processing step shown in FIG. 1 will be described. The slurry prepared as described above is cast (filled) into a mold of the prepared powder compact. As a filling method, the above-described slurry may be stored in a slurry pool or the like in advance, and a desired slurry may be cast (filled) from a prepared injection port. However, the present invention is not limited to such a slurry casting method, and is a known slurry casting method that does not deviate from the configuration of the present invention. Also good.

  For example, as shown in FIG. 2, when the powder compact is a turbine 1 with a shaft, slurry is cast into the powder compact mold 3 as shown in FIGS. After performing to a drying process, the below-mentioned (S3) hardening and cooling process process is performed.

[1-1-3] Slurry curing and cooling treatment process:
Furthermore, the (S3) slurry hardening and cooling process shown by FIG. 1 is demonstrated. After the slurry as described above is injected into a mold for molding a part of the powder molded body or the main body, the slurry is cured and cooled. In the slurry curing and cooling process, the cooling process is performed simultaneously while curing. As this curing treatment, it is preferable to cure alone or in combination such as 1) leaving for a predetermined time, 2) raising to a predetermined reaction temperature, 3) adding a catalyst immediately before casting, In terms of enabling rapid curing, it is more preferable to cure by 2) raising the temperature to a predetermined reaction temperature, or 3) adding a catalyst immediately before casting, either alone or in combination. In addition, as the cooling treatment, it is desirable that the slurry prepared as described above is poured into a mold for the powder molded body and cured, and at the same time, the mold containing the powder molded body is cooled. By cooling the mold containing the powder molded body while being poured and cured into the mold for the powder molded body, a temperature difference between the mold and the powder molded body in the mold is likely to occur. (S4) The mold release process step (1) can be easily performed. In addition, since the drying process is not performed, the solvent remains in the powder molded body. Therefore, the remaining solvent is likely to ooze out on the powder molded body during and after the cooling process, and the remaining solvent that has oozed out. However, it acts as a lubricant between the powder molded body and the mold for the powder molded body. That is, since the drying process is not performed before the later-described (S4) mold release process step (1), the solvent in the powder molded body is not completely evaporated, and the shrinkage of the powder molded body can be minimized. In addition, the remaining solvent in the molded body acts as a lubricant between the molded body mold / molded body, and the frictional force can be greatly reduced. In other words, a solvent layer can be formed between the mold / molded body, so-called “slip” between the mold / molded body can be improved, and the strength of the molded body found in complex shapes and the like tends to be low. In addition, the mold can be easily released without cracking.

  Specifically, the powder molded body 1 and the powder molding die 3 are subjected to a cooling process while being poured and cured in a powder molding die, as shown in FIGS. Between the powder molded body 1 and the powder molded body 1 in the region Z between the powder molded body 3 and the powder molded body 1 (region represented by the symbol Z in FIGS. 2 and 8). Thus, the frictional force is reduced and the mold release can be performed smoothly.

  Furthermore, it is preferable to produce a powder molded body by allowing the residual solvent remaining in the powder molded body to condense on the surface of the powder molded body mold during cooling. In this way, when cooling while curing, the residual solvent remaining in the powder molded body is condensed so as to be exposed on the surface of the powder molded body and the mold for the powder molded body, thereby forming the molded body. As described above, the dew condensation that occurs between the mold and the powder molded body molds as a lubricant and reduces the friction between the molded body and the powder molded body mold during the mold release. It can be performed smoothly and can be reliably released without being influenced by the thickness or complicated shape of the molded body. More specifically, the powder molded body and the powder molded body mold were cooled and left at room temperature to cause a temperature difference between the mold and the powder molded body, thereby remaining in the powder molded body. The solvent vapor pressure of the solvent increases, and it adheres between the powder molded body and the powder molded body mold, and adheres to the surface of the powder molded body and / or the surface of the powder molded body mold. Become. The solvent that exudes from the powder molded body by cooling as such a lubricant is transferred from the powder molded body mold to the powder molded body between the powder molded body / powder molded body mold. Thus, it is possible to suppress the friction generated during the mold release process for releasing the mold, to facilitate the mold release of the powder compact, and to eliminate the tearing.

  Further, it is preferable that the slurry at the time of casting containing the residual solvent is prepared so that the mold for the powder molded body has a smaller thermal conductivity and / or heat capacity than the slurry at the time of casting containing the residual solvent. . By being configured in this manner, a temperature difference is easily generated between the mold / molded body, and the effects of the present invention can be more easily achieved. On the other hand, when the powder molded body mold has a larger thermal conductivity and / or heat capacity than the casting slurry containing the residual solvent, the volume of the powder molded body mold is larger than that of the powder molded body. Since it is large, it is difficult to cause a temperature difference and it is difficult to achieve the effects of the present invention.

  Furthermore, the thermal conductivity of the powder molded body mold is preferably 0.5 W / mK or less, and the thermal conductivity of the powder molded body mold is more preferably 0.3 W / mK or less. As described above, when the thermal conductivity of the mold for the powder molded body is 0.5 W / mK or less, the temperature of the slurry is difficult to be transmitted to the mold, and a temperature difference is easily generated between the mold and the slurry, so that the mold release is easy. Therefore, it is preferable. Furthermore, it is more preferable that it is 0.3 W / mK or less because the temperature of the slurry is difficult to be transmitted to the mold, a temperature difference is surely generated between the mold and the slurry, and the mold release becomes easy. On the other hand, if the thermal conductivity of the residual solvent exceeds 0.5 W / mK, the temperature of the slurry is easy to be transferred to the mold, and the temperature of the slurry and the mold becomes difficult, and the temperature difference between the slurry and the mold is difficult to occur. This is not preferable because it becomes difficult to cause problems such as so-called tearing and cracks in the powder molded body.

The heat capacity of the powder molded body mold is preferably ³ MJ / m ³ K or less, and the heat capacity of the powder molded body mold is more preferably 2.5 MJ / m ³ K or less. Thus, when the heat capacity of the powder molded body mold is 3 MJ / m ³ K or less, the mold temperature tends to reach room temperature when placed at room temperature after the cooling treatment as described above, and the slurry / It is preferable because a temperature difference between the molds can be easily generated, and a later-described mold release process can be performed smoothly. Furthermore, it is more preferable that it is 2.5 MJ / m ³ K or less because the mold temperature easily reaches room temperature, and a temperature difference between the slurry and the mold is surely generated, so that the mold release process can be easily performed. On the other hand, if the heat capacity of the mold for the powder molded body exceeds ³ J / m ³ K, the mold temperature hardly reaches room temperature, and the temperature difference between the slurry / mold is difficult to occur. It is not preferable because it is easy.

  Further, the cooling temperature of the powder molded body is 10 ° C. or less with respect to room temperature, and the temperature between the powder molded body and the powder molding mold containing the powder molded body during cooling is further reduced. It is preferable to produce a powder molded body by releasing the mold by generating a difference, and more preferably, the cooling temperature of the powder molded body is 20 ° C. or lower with respect to room temperature, A temperature difference is generated between the molded body and the powder molding mold containing the powder molded body, and a mold release treatment is performed to manufacture the powder molded body. Thus, the cooling temperature of the powder molded body is 10 ° C. or less with respect to room temperature, and further, a temperature difference is generated between the powder molded body and the powder molding die containing the powder molded body. When the mold release process is performed and the powder molded body is manufactured, the slurry temperature is lowered, the temperature difference between the slurry / mold is likely to occur, and the temperature difference between the slurry / mold can be easily generated. This is preferable because it can be performed smoothly. Furthermore, when the above-mentioned treatment is performed at a cooling temperature of the powder compact of 20 ° C. or less with respect to room temperature, the slurry temperature is surely lowered and a temperature difference between the slurry and the mold is generated. Therefore, it is preferable. On the other hand, if the above-mentioned treatment is performed at a cooling temperature of the powder molded body of less than 10 ° C. with respect to room temperature, the slurry temperature is not sufficiently lowered and the temperature difference between the slurry and the mold is difficult to occur. This is not preferable because there is a high risk of occurrence of defects during mold processing.

  The cooling time of the powder compact is preferably at least 30 minutes or longer. Thus, it is preferable that the cooling time of the powder compact is at least 30 minutes or more because the temperature of the mold and the slurry is sufficiently lowered with respect to room temperature. On the other hand, when the cooling time of the powder compact is shorter than at least 30 minutes, the temperature of the mold and the slurry hardly changes with respect to room temperature, and the temperature difference between the slurry and the mold is difficult to occur before the mold release. This is not preferable because there is a high risk of occurrence of problems during processing.

[1-1-4] (S4) Mold release process (1):
Furthermore, (S4) mold release process step (1) shown in FIG. 1 will be described. Here, in the mold release process, for example, when the powder compact is a turbine as described later, the airfoil is released from the main body mold, and the powder compact body and its powder molding A clearance is maintained between the body mold and the later-described mold release process is performed more smoothly, and the powder compact body as described above is released from the powder compact body mold. (S6) This is different from the mold release process step (2). Therefore, although it is not an indispensable processing step, in order to ensure clearance when using a product used for molding a complex molded product, for example, an airfoil 9 as shown in FIG. 6B. , (S4) is preferably released in the step.

  The powder molded body mold 1 is composed of a powder molded body main body mold and a powder molded body remaining mold as shown in FIGS. When the molded body main body mold is composed of the lower mold 7, the lower shaft mold 15, the wing mold 9, the upper mold 5, etc., and the powder molded body remaining mold is composed of the upper shaft mold 11, etc. As shown in FIG. 8, the airfoil 9 may be slid so that the airfoil 9 is not completely released from the lower mold 7 and a clearance is formed between the powder compact and the airfoil 9.

[1-1-5] (S5) Drying step (1):
Next, (S5) drying process step (1) shown in FIG. 1 will be described. In this (S5) drying treatment step (1), for example, when the powder molded body is a turbine as described later, between the powder molded body main body and the mold for the powder molded body. The clearance is maintained, and the later-described (S6) mold release process step (2) is performed more smoothly. However, the drying process here does not completely dry the powder compact, and is a drying process that does not cause a problem during mold release.

  Further, it is more preferable that the powder molded body is cooled for at least 30 minutes or more and then allowed to stand at room temperature for 10 minutes or longer to produce a powder molded body. After the powder compact is cooled for at least 30 minutes or more and then allowed to stand for 10 minutes or more at room temperature, the powder compact is sufficiently cooled and further placed at room temperature. The vapor (condensation) of the solvent can be adhered between the molded body / powder molded body mold, and the condensed residual solvent can sufficiently serve as a lubricant. Therefore, it is preferable because the effects of the present invention can be reliably obtained. On the other hand, if the powder compact is allowed to stand for at least less than 30 minutes and / or less than 10 minutes at room temperature, it may not be cooled sufficiently or may be sufficiently cooled at room temperature. Since it is not placed, solvent vapor (condensation) cannot be adhered between the powder molded body / powder molded body mold. For this reason, the residual solvent that has condensed is not able to sufficiently function as a lubricant, and thus the effects of the present invention cannot be achieved.

[1-1-6] Molding process of powder compact and mold:
As described above, after the entire powder molded body is molded, the powder molded body is released from the powder molded body mold in the release processing step (2) shown in FIG. 1 (S6). For example, in a complicated shape product having a fine shape such as a turbine, as shown in FIG. 8, it is slid like a turbine blade portion (reference numeral 9 in FIG. 8) (S5) drying process ( 1), the shaft portion is also easily dried. Therefore, there is a clearance between the powder molded body and the powder molded body mold 3 due to drying shrinkage, and the upper shaft mold 11 and the upper The mold 5 is sequentially removed (released) and the powder molded body is pulled out from the lower mold 7 to obtain a molded body.

[1-1-7] Powder molded body drying treatment step:
Further, the drying process step (2) for drying the released powder compact (S7) will be described. In this (S7) drying process (2), unlike the above-mentioned (S5) drying process (1), the powder compact is completely dried. As such a drying processing means, for example, what is dried at 150 ° C. for 5 hours using desiccator storage, humidity conditioning drying, hot air drying, and the like can be given as an example. However, the present invention is not limited to such a drying means, and the drying process may be performed using a known drying means without departing from the present invention.

[1-2] Mold for powder molding:
The material and shape of the powder molding die are not particularly limited, and a mold made of a known material and shape is used as long as the effect of the present invention is achieved while adopting the configuration of the present invention. Also good. However, it is more preferable to produce a powder molded body using a mold in which the material of the powder molded body mold is made of polytetrafluoroethylene. When a mold made of such a material is used, a temperature difference tends to occur between the powder molded body and the powder molded body mold during cooling. That is, a mold made of a material such as polytetrafluoroethylene is preferable because it easily returns to room temperature when allowed to stand at room temperature, so that a temperature difference from the powder molded body is produced and the effects of the present invention can be reliably achieved. On the other hand, for example, in a powder molded body mold in which aluminum is diamond-like carbon coated (DLC coated), the temperature of the powder molded body is easily transmitted, so that a temperature difference from the powder molded body hardly occurs. Further, it is not preferable because adhesion of the solvent such as condensation of the residual solvent is not sufficiently performed.

  When the powder compact is a shaft-equipped turbine compact, as shown in FIGS. 3, 4, and 6A, after attaching the airfoil to the powder compact, the slurry is added to the slurry. The effects of the present invention are also widely used in the case of manufacturing a shaft-equipped turbine molded body having a complicated shape by, for example, passing through the processing steps described so far after being cast into a main body mold and cured. Can play.

  Furthermore, the manufacturing method of this embodiment is demonstrated, referring a figure about the case where a powder compact is a molded object for turbines with a shaft.

  First, as shown in FIGS. 2, 3, and 5, a lower shaft mold 15 for forming a tip shaft 17 a formed at the tip of the turbine 1 with a shaft, and a lower shaft mold 15 are stably placed. A lower mold 7 is prepared. The lower mold 7 is formed with a plurality of holes (fixed pin insertion holes 7a) into which a fixing pin 19 to be described later can be inserted, and an insole 7b (see FIG. 3) that is not penetrated is formed. The mold 15 is used by being fitted (inserted) into the center thereof. Further, in order to form the tip shaft 17a in the lower shaft mold 15, a slurry casting hole 15a that can be poured (filled) through the slurry casting hole 11a formed in the upper shaft mold 11 is formed in the center. Is formed. The lower mold 7 shown in FIGS. 3 and 4 is formed in a circular shape. However, the lower mold 7 is not limited to such a circular mold shape, and may be a polygon, an ellipse, or the like as necessary. Preferably it is selected.

  Next, an airfoil 9 for forming a turbine main body including a blade portion of a turbine with a shaft is set on the lower shaft die 15 and the lower die 7 as shown in FIG. 6A. In addition, it is preferable to form a plurality of fixing pin insertion holes 9b into which the fixing pin can be inserted in the airfoil 9 here, because the airfoil can be fixed. Further, during the mold release process of (S4) described above, If the slit 7c (see FIG. 5) that allows the airfoil 9 to slide is formed so that the clearance between the airfoil 9 and the airfoil portion 3b can be secured, the airfoil can be easily slid without removing the fixing pin. Therefore, it is preferable.

  Further, an upper die 5 as shown in FIG. 3, FIG. 7A, and FIG. 7B is prepared, and is set on the lower shaft die 15 and the airfoil 9 set on the lower die 7 as described above. Here, when the fixed die insertion hole, the vertical die positioning pin insertion hole 21 and the like are also formed in the upper die 5 here, the upper die 7 and the lower die 7 are connected to the upper die 7 via the fixed pin or the vertical die positioning pin 23 and the like. Since the so-called split mold as described above can be integrated, the molded body can be further fixed.

  In addition, it is preferable that the fixing pins and the upper and lower positioning pins here are formed so as to be removable at the time of releasing. For example, it can be freely inserted into and removed from the tip shaft mold (lower shaft mold), wing mold, and upper mold as described above. The thing etc. in which such a play is formed can be used suitably.

  Further, an upper shaft mold 11 for forming the upper shaft, which is a turbine with a shaft, is prepared (see FIG. 3), set on the upper mold 5, and set by inserting the upper and lower mold positioning pins 23. In this way, after setting the shaft turbine mold, the desired slurry as described above is poured into the upper slurry casting hole (upper shaft mold 11 as shown in FIGS. 2 and 4). From the slurry casting hole 11a).

  Next, a curing and cooling process is performed. Specifically, in a refrigerator or the like, the temperature is set to 10 ° C. or lower to 20 ° C. or lower than room temperature, and is cooled for at least 30 minutes or more and left at room temperature to cause a temperature difference between the mold and the powder compact.

  Thereafter, the fixing pin 19 is pulled out and the airfoil 9 is slid as shown in FIG. 8 to create a space between the airfoil part and the airfoil. Ensure clearance.

  Furthermore, a drying process is performed. Specifically, it is dried at 40 ° C. for 1.0 hour using hot air drying.

  Thereafter, the fixing pin 19 and the like shown in FIG. 3 are removed, and the upper shaft mold 11, the upper mold 5, the wing mold 9, and the lower shaft mold 15 are removed, and the powder compact is released.

  Furthermore, after performing the mold release treatment of the powder molded body as described above, the powder molded body is completed by drying at 150 ° C. for 5.0 hours.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[1] Failure mode:
For each of the obtained molded products of Examples and Comparative Examples, it was evaluated whether or not a defect occurred by performing blade blade tearing observation and blade crack observation.

[1-1] Observation of wings:
The blades of the obtained turbine with a shaft were observed visually or using a loupe or the like for the presence or absence of tearing in the blades. As an evaluation method, the percentage of the number of blades in which the number of blades is broken out of the number of molded products (n) is shown in 100% (%).

[1-2] Wing crack observation:
The obtained blade of the turbine with a shaft was observed for cracks in the blade by visual observation or using a magnifying glass. As an evaluation method, the percentage of the number of blades in which blade cracks were generated out of the number of molded products (n) was shown as a percentage (%).

[2] Total good product rate:
Each of the obtained molded products of Examples and Comparative Examples was evaluated for the presence or absence of defects such as tears and cracks in the wing. As an evaluation method, out of the number of molded products (n), the number of blades that were not broken and cracked in the blades was shown as a percentage (%).

[3-1] Production of mold for powder compact:
As a powder molding die in Examples and Comparative Examples, a molding die A having a shape as shown in FIGS. 2 to 5B was produced while being molded from polytetrafluoroethylene. Specifically, the mold A used in Examples 1 and 2 below is a polytetrafluoroethylene having a thermal conductivity of 0.25 W / mK and a heat capacity of 2.2 MJ / m ³ K at 20 ° C. as a mold material. Molded mold A was used.

Furthermore, as a powder molding die in the comparative example, aluminum was used as a material, and DLC coating was performed, and a molding die B having a shape as shown in FIGS. Specifically, a mold B used in Comparative Example 6 below is a mold B formed by DLC coating on aluminum having a conductivity of 237 W / mK and a heat capacity of 2.38 MJ / m ³ K at 20 ° C. as a mold material. It was used.

[4] Preparation of powder compact:
Example 1
After adding and mixing 1.6 parts by mass of a dispersant made of a polycarboxylic acid copolymer to 28.3 parts by mass of a dispersion medium made of dibasic acid methyl ester at room temperature (around 20 ° C.), the slurry was nitrided It was prepared by adding and dispersing 67 parts by mass of silicon powder, adding 0.4 parts by mass of an isocyanate resin as a gelling agent, and then adding 0.2 parts by mass of dimethylaminohexanol.

  The molded body was prepared by injecting the slurry prepared as described above into the powder molded body mold A prepared as described above, and then leaving the molded body together with the mold A in a refrigerator at a temperature of 18 ° C. for 3 hours. Then, it was cooled and cured, and then taken out from the refrigerator and released to form three powder compacts. Each powder molded body thus obtained was used as the powder molded body of Example 1 and evaluated as described above. The characteristics at that time and the evaluation of the obtained molded product are shown in Table 1.

(Example 2)
In the same manner as in Example 1, the slurry prepared as described above was poured into a mold A for a powder compact. Furthermore, the molded body together with the mold A is allowed to cool and cure in a refrigerator at a temperature of −10 ° C. for 0.5 hours, and then taken out from the refrigerator and left at room temperature (temperature of 18 ° C.) for 3 hours. Thereafter, 17 powder compacts were formed by releasing the mold. Each powder molded body thus obtained was used as the powder molded body of Example 2 and evaluated as described above. The characteristics at that time and the evaluation of the obtained molded product are shown in Table 1.

(Comparative Example 1)
In the same manner as in Example 1, the slurry prepared as described above was poured into a mold A for a powder compact. Further, the molded body, together with the mold A, was placed in a hot air dryer and allowed to stand at a temperature of 40 ° C. for 10 hours to be cured by heating and dried. Then, it took out from the hot air dryer and mold-processed four powder compacts. Each powder molded body thus obtained was used as the powder molded body of Comparative Example 1 and evaluated as described above. The properties at that time and the evaluation of the obtained molded product are shown in Table 2.

(Comparative Example 2)
As in Comparative Example 1, the slurry prepared as described above was poured into a mold A for a powder molded body, and the molded body together with the mold A was placed in a hot air dryer and left at a temperature of 40 ° C. for 2 hours. Heat-cured and dried. Then, it took out from the hot air dryer and mold-processed four powder compacts. Each powder molded body thus obtained was used as a powder molded body of Comparative Example 2 and evaluated as described above. The properties at that time and the evaluation of the obtained molded product are shown in Table 2.

(Comparative Example 3)
As in Comparative Example 1, the slurry prepared as described above was poured into a mold A for a powder molded body, and the molded body together with the mold A was placed in a hot air dryer and left at a temperature of 40 ° C. for 1.5 hours. Then, it was cured by heating and dried. Then, one powder compact was shape | molded by taking out from a hot air dryer and performing a mold release process. The powder molded body thus obtained was used as the powder molded body of Comparative Example 3 and evaluated as described above. The properties at that time and the evaluation of the obtained molded product are shown in Table 2.

(Comparative Example 4)
As in Comparative Example 1, the slurry prepared as described above was poured into a mold A for a powder molded body, and the molded body together with the mold A was placed in a hot air dryer and left at a temperature of 40 ° C. for 1.0 hour. Then, it was cured by heating and dried. Thereafter, 10 powder compacts were molded by taking out from the hot air dryer and releasing the mold. Each powder molded body thus obtained was used as a powder molded body of Comparative Example 4 and evaluated as described above. The properties at that time and the evaluation of the obtained molded product are shown in Table 2.

(Comparative Example 5)
As in Comparative Example 1, the slurry prepared as described above was poured into a mold A for a powder molded body, and the molded body together with the mold A was placed in a hot air dryer and left at a temperature of 40 ° C. for 0.5 hour. Then, it was cured by heating and dried. Then, it took out from the hot air dryer and carried out mold release process, and formed two powder compacts. Each powder molded body thus obtained was used as a powder molded body of Comparative Example 5 and evaluated as described above. The properties at that time and the evaluation of the obtained molded product are shown in Table 2.

(Comparative Example 6)
The slurry prepared as described above was poured into a mold B for a powder compact. Further, the molded body together with the mold B was allowed to cool and cure in a refrigerator at a temperature of −10 ° C. for 0.5 hours, and then removed from the refrigerator and left at room temperature (temperature of 18 ° C.) for 3 hours. Thereafter, one powder compact was formed by releasing the mold. The powder molded body thus obtained was used as the powder molded body of Comparative Example 6 and evaluated as described above. The characteristics at that time and the evaluation of the obtained molded product are shown in Table 1.

(Discussion 1)
From the results of Examples 1 and 2, by casting the slurry and then cooling the mold together, it is possible to reduce blade damage such as wing breakage and blade cracking during mold release (when the mold is pulled out). Good results could be obtained. In particular, in Examples 1 and 2, (i) by not drying the solvent, shrinkage is minimized, (ii) strength after curing of the molded body is maintained, and (iii) the solvent of the molded body is the mold. / The fact that the friction force between the mold and the molded body was greatly reduced at the time of mold release due to the adhesion to the molded body, which is considered to have reduced the blade damage, which was supported by the experimental results.

  On the other hand, in Comparative Examples 1 to 5, since the curing treatment was performed without cooling, there was no residual solvent that played the role of lubricating oil, as seen in the examples, and the frictional force between the mold and the molded body was Since it is large, the blades are broken at the time of mold release, and defects such as cracks are greatly generated. From this, it was confirmed that in Comparative Examples 1 to 5, the effects of the present invention could not be achieved, but problems remained in practical use.

  Furthermore, in Comparative Example 6, an experiment was performed as described above using a mold made of aluminum, but the blades were cut off at the time of mold release. This is presumably because in the mold made of aluminum, the base material was a metal during cooling, and the temperature of the mold and the molded body became substantially the same during cooling, so that the residual solvent did not ooze out. From the above, since the polytetrafluoroethylene mold does not cool very much, the solvent vapor pressure between the mold and the molded body rises due to the temperature difference and adheres to the mold surface, which acts as a lubricant, and the mold is easily removed. Therefore, it is preferable as the material of the mold, but it was confirmed that the mold made of metal such as aluminum is not preferable as the material of the mold.

  Furthermore, in Examples 1 and 2, by casting the slurry and then cooling the mold together, it is possible to reduce blade damage such as wing breakage and blade cracking during mold release (when the mold is pulled out). Good results could be obtained. However, in Comparative Example 6, since the mold base material had high conductivity and heat capacity, and the temperature between the mold and the molded body became almost the same during cooling, the residual solvent did not bleed out as in the example. It was thought to be difficult to mold and was proved by experiments. The same effect can be obtained by casting the slurry into a mold that has been cooled in advance.

  According to the method for producing a powder molded body according to the present invention, it is excellent in releasability, can hardly control the drying shrinkage difference, can control the drying shrinkage difference, can suppress the product variation, can improve the dimensional accuracy, and can be produced. The effect which can improve property can be show | played. Not only can it be suitably used for manufacturing a shaft-formed turbine molded body, but it can also be applied to arc tube applications as exemplified in WO 2007/111380.

1: Powder compact (turbine shaft with shaft, turbine with shaft), 3: Mold for powder compact, 5: Upper die, 7: Lower die, 7a: Fixed pin insertion hole, 7b: Insole, 7c: (Lower mold) slit, 7d: (Upper and lower mold positioning) pin insertion hole, 9: Wing mold, 9b: Fixed pin insertion hole, 11: Upper shaft mold, 11a: Slurry casting hole, 15: Lower shaft mold, 17a : Tip axis, 19: fixing pin, 21: vertical die positioning pin insertion hole, 23: vertical die positioning pin, Z: region between the powder molding die 1 and the powder compact 3.

Claims (11)

A method for producing a powder molded body in which a slurry containing a ceramic and / or metal powder, a dispersion medium, and a gelling agent is cast, and the slurry is solidified by gelation to obtain a molded body. And
The slurry is poured into a mold for a powder molded body, and then cooled together with the mold containing the powder molded body while being cured, thereby causing a temperature difference between the mold and the powder molded body to release the mold. A method for producing a powder molded body, which is processed to produce the powder molded body.   2. The powder molded body according to claim 1, wherein the cooled powder molded body is subjected to a mold release treatment by causing a temperature difference between the mold and the powder molded body together with the housed mold at room temperature to manufacture the powder molded body. Method for producing a powder compact.   3. The method for producing a powder compact according to claim 1, wherein the powder compact is produced by causing condensation of a residual solvent remaining in the powder compact on the surface of the mold during the cooling. 4.   The mold according to any one of claims 1 to 3, wherein the mold is manufactured using a mold having a thermal conductivity and / or a heat capacity smaller than that of a slurry containing a residual solvent at the time of casting. The manufacturing method of the powder molded object of description.   The method for producing a powder compact according to claim 4, wherein the thermal conductivity of the mold is 0.5 W / mK or less. The method for producing a powder compact according to claim 4, wherein the mold has a heat capacity of 3 MJ / m ³ K or less.   The method for manufacturing a powder molded body according to any one of claims 1 to 6, wherein the powder molded body is manufactured using a mold made of polytetrafluoroethylene.   The cooling temperature of the powder molded body is 10 ° C. or less with respect to room temperature, and further, during the cooling, between the powder molded body and the powder molding mold containing the powder molded body The method for producing a powder molded body according to any one of claims 1 to 7, wherein the powder molded body is produced by generating a temperature difference and releasing the mold.   The method for producing a powder compact according to any one of claims 1 to 8, wherein the cooling time of the powder compact is at least 30 minutes or longer.   The method for producing a powder molded body according to any one of claims 1 to 9, wherein the powder molded body is cooled for at least 30 minutes or more and then allowed to stand at room temperature for 10 minutes or longer to produce a powder molded body. .   The method for producing the powder molded body according to any one of claims 1 to 10, wherein the powder molded body is a molded body for a turbine with a shaft.

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