JP2005336525A - Composite powder for forming metal product and method for manufacturing granular material for forming, and method for producing metal product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide composite powder for forming a metal product with which relative density of a formed body can remarkably be improved, to provide a method for manufacturing a granular material for forming with which waste material etc., having comparatively large grain diameter, such as metallic waste material, can be made to fine powder with a simple treatment using a jet-mill and to provide a method for producing the metal product with which the metal product obtaining the compactness of pressed powdery body and excellent in mechanical strength. <P>SOLUTION: This composite powder for forming the metal product, has a constitution of metal fine powder having 0.1-5 μm average grain diameter, press-stuck and composed on the surface of metal coarse powder having 5.5-15 μm average grain diameter. This method for manufacturing the granular material for forming, has the constitution provided with a pulverizing process for obtaining the metal fine powder, a composing process for composing the metal fine powder on the surface of the metal coarse powder and a granular process for granulating the composite powder into the granular material having 1-5 mm grain diameter. This method for producing the metal product, has the constitution provided with the forming process for forming by filling the granular material for forming into a forming mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a composite powder for molding a metal product and a granular material for molding used in molding a metal product by press molding or injection molding, and a method for producing a metal product.

Conventionally, as a method for forming a metal material into a predetermined shape and obtaining a metal product such as a machine part, there are methods by casting, forging, rolling, etc., and in particular, the metal product to be obtained has a precise and complicated shape. When it has what it has or high mechanical strength, it was common to manufacture by casting. However, in the case of manufacturing by casting, a press work or the like for cutting and removing a pouring gate or the like after casting is required, and the work is complicated. Therefore, a powder metallurgy method is used in which metal powder is used as a metal material, pressed to obtain a green compact, and then sintered to obtain a metal product. 1 is described.
As the metal powder used in the powder metallurgy described in Patent Document 1, a metal powder having a particle diameter of 1 μm to 100 μm manufactured by a gas atomizing method, a water atomizing method, a plasma atomizing method or the like is usually used.
Thus, a comparatively fine metal powder can be obtained by using the atomizing method. In powder metallurgy, etc., as the metal powder becomes finer, the relative density of the green compact can be increased, and shrinkage during sintering is less likely to cause dimensional errors, and a metal product with high mechanical strength can be obtained. It is done.

JP 2002-294308 A

However, the above conventional techniques have the following problems.
(1) The metal powder obtained by the gas atomization method, water atomization method, plasma atomization method, etc. is classified so that it has a uniform size and a spherical shape. Therefore, there is a problem that it is difficult to obtain a metal product having a desired high mechanical strength.
(2) In addition, the gas atomization method, water atomization method, plasma atomization method, and the like can obtain a relatively fine metal powder, but there is a problem that the metal material is melted at the time of manufacturing the metal powder and the productivity is insufficient. Had.
(3) The granulated powder described in Patent Document 1 is obtained by pulverizing a lump powder obtained by pre-sintering a fine powder having an average particle size of 30 μm or less, and has an average particle size of 350 μm or less. Therefore, there is a problem that the handling property at the time of loading / unloading and filling into a mold is remarkably lacking.
(4) Further, since only fine powder having an average particle diameter of 30 μm or less is used, there is a limit to densification of the green compact, and the relative density of the green compact is about 75%. About 93 to 95%, there was a problem that high mechanical strength could not be realized.

The present invention solves the above-mentioned conventional problems, can remarkably improve the relative density of the molded body, can increase the mechanical strength of the molded body, and can obtain a product with high dimensional accuracy. It aims at providing the composite powder for metal product shaping | molding.
In addition, the present invention solves the above-described conventional problems, and removes metal wastes that have been punched out and wastes with relatively large particle sizes that have become unnecessary by the gas atomization method, etc., by simple processing using a jet mill. An object of the present invention is to provide a method for producing a granular material for molding that is easy to handle and suitably used when molding a metal product by press molding or injection molding, etc., because it can be made into a powder and is excellent in labor saving and cost saving. To do.
In addition, the present invention solves the above-described conventional problems, and removes metal wastes that have been punched out and wastes with relatively large particle sizes that have become unnecessary by the gas atomization method, etc., by simple processing using a jet mill. Metal that can be made into powder, so it is excellent in labor-saving and cost-saving, has excellent productivity, can be compacted in the green compact, and can obtain a metal product with excellent mechanical strength without cracks and cracks It aims at providing the manufacturing method of a product.

In order to solve the above-mentioned problems, a method for producing a composite powder for metal product molding and a granular material for molding and a method for producing a metal product according to the present invention have the following configurations.
The composite powder for molding metal products according to claim 1 of the present invention is obtained by pressing a metal fine powder having an average particle size of 0.1 μm to 5 μm to the surface of a metal coarse powder having an average particle size of 5.5 μm to 15 μm. It has a composite structure.

This configuration has the following effects.
(1) A metal fine powder having an average particle size of 0.1 μm to 5 μm is pressed onto a surface of a coarse metal powder having an average particle size of 5.5 μm to 15 μm to form a composite mold. When filled and molded, metal fine powder enters the gaps between the coarse metal powders, and the relative density of the molded body can be significantly improved to 94% to 98%, which can increase the mechanical strength of the molded body. it can. In addition, when the molded body is sintered after molding, it is possible to obtain a product with a small shrinkage ratio of the molded body due to sintering, high dimensional accuracy, and a high sintered density and excellent mechanical strength. Can do.

Here, as the material of the metal fine powder and the metal coarse powder, aluminum (Al), iron (Fe), carbon steel, stainless steel, tungsten (W), zinc (Zn), lead (Pb), tungsten carbide (WC) ), Titanium (Ti), cobalt (Co), or alloys thereof. The metal fine powder and the metal coarse powder are the same or different metal species.
Moreover, when the average particle diameter of the metal fine powder is smaller than 0.1 μm, it is not preferable because it is easy to activate and various chemical reactions are likely to occur, and when it is larger than 5 μm, it is not preferable because the density of the formed body tends to decrease. On the other hand, if the average particle size of the coarse metal powder is smaller than 5.5 μm, it is not preferable because it has a problem that it is difficult to combine with a small fine powder due to lack of affinity. On the other hand, if it is larger than 15 μm, the voids become large and the density decreases, which is not preferable.

  The method for producing a molding granule according to claim 2 of the present invention includes a pulverization step of pulverizing a metal material to obtain fine metal powder having an average particle size of 0.1 μm to 5 μm, and an average particle size of 5.5 μm. A compounding step of compounding the metal fine powder on the surface of a ~ 15 μm metal coarse powder, and a granulating step of granulating the compounded powder obtained in the compounding step into a granular material having a particle size of 1 mm to 5 mm And a configuration provided with.

This configuration has the following effects.
(1) A metal fine powder having an average particle size of 0.1 μm to 5 μm obtained by pulverizing a metal material is pressed onto a surface of a metal coarse powder having an average particle size of 5.5 μm to 15 μm to be combined, Since the composite powder can be granulated to form a granular material, when the granular material is filled into a mold and molded, the metal fine powder enters the gaps between the metal coarse powders, and the relative shape of the molded body The density can be remarkably improved to 94% to 98%, and the mechanical strength of the molded body can be increased. In addition, when the molded body is sintered after molding, it is possible to obtain a product with a small shrinkage ratio of the molded body due to sintering, high dimensional accuracy, and a high sintered density and excellent mechanical strength. Can do.
(2) In the compounding step, the metal fine powder is coated on the surface of the metal coarse powder to form a composite, so that the fine particles contained in the granulated particles in the granulation step are contained almost uniformly. Therefore, when filling the mold with the granular material, the metal fine powder surely enters the gaps between all the metal coarse powders, preventing the variation of the relative density of the molded body and improving the mechanical strength. be able to.
(3) In the pulverization step, metal fine powder having a sharp particle size distribution can be easily obtained in a short time, and the yield of metal fine powder having an average particle size of 0.1 μm to 5 μm can be increased.
(4) By granulating into a granular material having a particle size of 1 mm to 5 mm in the granulation step, it becomes easy to carry in and out in the subsequent step, and particularly when the mold is filled in the molding step, etc. There is no problem that the metal powder enters between the female molds, and the handling property can be improved.

  Here, as a metal material for pulverizing to obtain a metal fine powder, it is the above-described material, and waste generated in the manufacturing process of metal products by casting or aluminum die casting, for example, cut and removed spout, It is possible to use a crushed material, a defective product such as a deformation or a flaw generated at the time of punching. In addition, before the crushing process, a crushing process for crushing the metal material and a classification process for classifying the crushed material can be provided. As a result, the metal material is crushed in the crushing step, classified in the classification step to obtain a relatively fine crushed material, and the crushed material is crushed in the crushing step. A metal powder having a distribution can be obtained in a short time and with a small amount of energy.

  In the pulverization step, a pulverizer such as a jet mill is used. In particular, as a pulverization nozzle for injecting high-pressure gas into a swirling pulverization chamber, the injection part is provided with a slit-shaped injection port formed in a slit shape, or the central axis of the slit-shaped injection port and the slit-shaped injection port. One or a plurality of circular injection ports formed so that the center is located on the passing central axis, and a slit-shaped high-pressure gas flow path communicating with the circular injection port, or A slit-shaped injection port and a slit-shaped high-pressure gas channel communicating therewith, and the slit-shaped high-pressure gas channel having a predetermined twist angle with the central axis at the slit-shaped injection port are used. Thereby, since the velocity of the injected gas flow is difficult to decrease, the eccentricity of the swirl flow hardly occurs, and a concentric ideal swirl flow is formed. Even if the pressure of the gas flow is increased to about 15 MPa, the swirl flow is not decentered, the concentric swirl flow can be maintained, and no blowback occurs. It can grind | pulverize and a 0.1 micrometer-5 micrometer metal fine powder can be obtained with a high yield.

The metal coarse powder can be obtained by pulverizing and classifying a metal material with a pulverizer such as a jet mill in the same manner as the metal fine powder. The shape of the metal fine powder or the metal coarse powder is formed into a flake shape, a spherical shape, a plate shape, a needle shape, or the like by pulverization. In particular, flakes, plates, and needles are preferable because voids are not easily formed between the metal coarse powders when the mold is filled and molded, and the compact can be densified.
The fine metal powder obtained in the pulverization process is recovered with or without classification using a bag filter, cyclone, forced vortex classifier, etc., and the average particle size is 0.1 μm to 5 μm. It is preferable to obtain a fine metal powder having a sharp edge.

In the compounding step, a pulverizer or a granulator such as a jet mill or a mixer is used. In the compounding, in the crushing chamber of a crusher or the like, the metal fine powder is made to collide with the surface of the metal coarse powder that becomes the core, thereby causing the metal fine powder to be pressed into a dotted shape, a film shape, etc. This is done by coating.
In the granulation step, a granulator such as a rotating pan, a rotating drum, or a high-speed mixer is used. Also, before the granulation step, a mixing step of mixing the composite powder and a binder such as an organic binder is provided, or the composite powder and the binder are put into a granulator and granulated while mixing. May be. As the binder, paraffin wax, polyethylene, gelatin or the like is used. When a binder is added, the binder is removed by appropriately heating after molding at a predetermined temperature.

  The manufacturing method of the granular material for shaping | molding of Claim 3 of this invention has the structure which grind | pulverizes the said metal material in inert gas atmosphere in the said grinding | pulverization process in invention of Claim 2. .

With this configuration, in addition to the operation of the second aspect, the following operation is provided.
(1) By crushing the metal material in an inert gas atmosphere in the crushing step, it is possible to prevent an oxide film from being formed on the surface of the metal powder and to prevent a decrease in mechanical strength.
(2) Dust explosion can be prevented by pulverizing in an inert state even when a metal material that is prone to explosion due to oxidation is used.

  According to a fourth aspect of the present invention, there is provided a method for producing a granular material for molding according to the second or third aspect, wherein the metal material is pulverized using a horizontal swirling jet mill in the pulverization step. A method for producing a granular material for a product, wherein a pulverizing nozzle that forms a swirling flow of the jet mill includes an injection unit that injects gas, and the injection unit includes a slit-like injection port formed in a slit shape, and the slit One or a plurality of circular injection ports formed so that the center is positioned on a central axis passing through the central axis of the cylindrical injection port, and the slit-shaped high-pressure gas flow path communicating with the slit-shaped injection port and the circular injection port And a configuration provided with.

With this configuration, in addition to the operation of the second or third aspect, the following operation is provided.
(1) Since the injection unit has a circular injection port, the flow rate of the gas flow injected from the circular injection port is large and the energy is large, so the edge-like gas flow injected from the slit injection port is a circle. Concentric circles are less likely to cause eccentricity of swirling flow because they are dragged by the gas flow injected from the shape injection port, and even if the distance from the injection section is far away, the edge-shaped gas flow hardly swirls and the gas flow speed is difficult to decrease. An ideal swirling flow is formed, and metal materials made of various metals or alloys that have been difficult to pulverize can be pulverized in a short time.
(2) Further, since the gas flow injected from the pulverization nozzle is not easily disturbed, a concentric circular flow can be maintained in the swirl pulverization chamber without being eccentric even if the pressure of the gas flow is increased to about 15 MPa. As the pressure is increased, the kinetic energy of the pulverizer can be increased, enabling the pulverization of high energy pulverizers, enabling the formation of fine metal powders with a sharp particle size distribution in a short time. Can get to.

  Here, as the slit-shaped injection port, those formed in a substantially rectangular shape, a substantially oval shape, a substantially bowl shape, etc., or those formed by combining them into a cross shape or a radial shape are used. The ratio of the short side length W to the long side length L (W: L, referred to as aspect ratio) of the slit-shaped injection port is 1: 2 to 1:30, preferably 1: 5 to 1. : 22 is preferably used. As the aspect ratio becomes smaller than 1: 5, the entrainment vortex increases, the velocity distribution of the gas injected from the injection section tends to spread and the energy tends to diffuse, and as the aspect ratio becomes larger than 1:22, the energy efficiency tends to decrease. Since it is seen, it is not preferable. In particular, when the ratio is smaller than 1: 2 or larger than 1:30, these tendencies become remarkable, so that neither is preferable.

  As the circular injection port, one formed in a circular shape, an elliptical shape or the like is used. As the inner diameter of the circular injection port, 1.1 to 3 times the length W of the short side of the slit injection port is preferably used. As the inner diameter becomes smaller than 1.1 times the length W of the short side of the slit-shaped injection port, it is difficult to obtain the effect of forming the circular injection port, and the edge-shaped gas flow easily vortexes at a short distance from the injection unit. There is a tendency that the gas flow velocity tends to decrease, and as it becomes larger than three times, the vortex increases in the gas flow injected from the circular injection port, the gas flow velocity decreases, and the energy loss increases. Therefore, neither is preferable. In addition, the internal diameter of the circular shaped injection port formed in elliptical shape shall mean a long diameter. Note that the high pressure gas flow is rectified by the slit-shaped high pressure gas flow path, and the flux is hardly disturbed by the inertial force, so that high energy can be maintained.

  Moreover, it can replace with a circular shaped injection port, and can be provided with the groove part formed in the several place of the long side of the slit-shaped injection port at predetermined intervals. Thereby, since the groove part formed at predetermined intervals in at least a plurality of locations on the long side of the slit-like injection port is provided, the gas flow injected from the slit-like injection port is unlikely to be disturbed, and the gas flow rate is high. Because it is difficult to reduce, the eccentricity of the swirling flow is difficult to occur, and an ideal concentric swirling flow is formed. It can be carried out. As the groove portion, one formed at least at a plurality of locations on the long side is used. This is because the edge-like gas flow injected from the slit-like injection port is easily disturbed on the long side, and can be prevented. In addition, it can also form in multiple places of a short side as needed. Moreover, as a groove part, what was formed over the full length of a slit-shaped high pressure gas flow path is used suitably. This is because the rectifying effect can be enhanced.

  According to a fifth aspect of the present invention, there is provided a method for producing a metal product, wherein a molding die is filled with the molding granule obtained by the molding granule manufacturing method according to any one of the second to fourth aspects. And has a configuration for molding.

This configuration has the following effects.
(1) A molded product can be obtained by filling a molding die with a molding die and molding it using press molding, injection molding or the like. At this time, the molding granular material is crushed and compressed in the molding die, and the metal fine powder enters the gaps between the coarse metal powders to fill the gaps. It can be remarkably improved to 98%, and the mechanical strength of the molded body can be increased.
(2) Further, by molding a molding granulate obtained by granulating the composite powder and obtaining a molded body, a metal product having high mechanical strength can be obtained without sintering.

  Here, as a molding method in the molding process, hot press, cold press, hot isostatic pressing (HIP), cold isostatic pressing (CIP) press molding, MIM injection molding or the like can be used. . In particular, when performing press molding, it is preferable to use a vibration press device. Thereby, the packing density in the shaping | molding die of a granular material can be raised by vibration, and the mechanical strength of a metal product can further be raised. In addition, when performing injection molding such as MIM, an apparatus similar to that when performing synthetic resin injection molding can be used.

  According to a sixth aspect of the present invention, there is provided a metal product manufacturing method according to the fifth aspect of the invention, comprising a sintering step of sintering the formed body formed in the forming step. .

With this configuration, in addition to the operation of the fifth aspect, the following operation is provided.
(1) The mechanical strength of the metal product can be increased by sintering in the sintering step.

  Here, in the sintering process, an inert gas atmosphere furnace, a reducing atmosphere furnace, a vacuum heating furnace, or the like is used. As the sintering temperature, a suitable temperature can be used for each type of metal material.

As described above, according to the metal product manufacturing method of the present invention, the following advantageous effects can be obtained.
According to the invention of claim 1,
(1) A metal fine powder having an average particle size of 0.1 μm to 5 μm is pressed onto a surface of a coarse metal powder having an average particle size of 5.5 μm to 15 μm to form a composite mold. When filled and molded, metal fine powder enters the gaps between the coarse metal powders, and the relative density of the molded body can be significantly improved to 94% to 98%, which can increase the mechanical strength of the molded body. it can. In addition, when the molded body is sintered after molding, it is possible to obtain a product with a small shrinkage ratio of the molded body due to sintering, high dimensional accuracy, and a high sintered density and excellent mechanical strength. It is possible to provide a composite powder for forming a metal product.

According to invention of Claim 2,
(1) A metal fine powder having an average particle size of 0.1 μm to 5 μm obtained by pulverizing a metal material is pressed onto a surface of a metal coarse powder having an average particle size of 5.5 μm to 15 μm to be combined, Since the composite powder can be granulated to form a granular material, when the granular material is filled into a mold and molded, the metal fine powder enters the gaps between the metal coarse powders, and the relative shape of the molded body The density can be remarkably improved to 94% to 98%, and a method for producing a molding granular material that can increase the mechanical strength of the molded body can be provided.
(2) In the compounding step, by forming a composite by coating the surface of the metal coarse powder with metal fine powder, variations in the relative density of the molded product can be prevented and the mechanical strength can be improved. A method for manufacturing a product can be provided.
(3) In the pulverization step, a metal fine powder having a sharp particle size distribution can be easily obtained in a short time, and the molding particle capable of increasing the yield of the metal fine powder having an average particle size of 0.1 μm to 5 μm. A method for manufacturing a product can be provided.
(4) By granulating into a granular material having a particle size of 1 mm to 5 mm in the granulation step, it becomes easy to carry in and out in the subsequent step, and particularly when the mold is filled in the molding step, etc. It is possible to provide a method for producing a molding granule that can improve the handleability without causing a problem that the metal powder enters between the female molds.

According to invention of Claim 3, in addition to the effect of Claim 2,
(1) A granular material for molding capable of preventing an oxide film from being formed on the surface of the metal powder and preventing a decrease in mechanical strength by pulverizing the metal material in an inert gas atmosphere in the pulverization step. The manufacturing method of can be provided.
(2) To provide a method for producing a molding granular material with excellent safety capable of preventing a dust explosion by pulverizing in an inactive state even when a metal material that is prone to explosion due to oxidation is used. be able to.

According to invention of Claim 4, in addition to the effect of Claim 2 or 3,
(1) Since the injection part has a circular injection port, the eccentricity of the swirling flow is not easily generated, and a concentric ideal swirling flow is formed. Various metals or alloys that have been difficult to pulverize until now A metal material made of the above can be finely pulverized in a short time, and a method for producing a granular material for molding excellent in pulverization efficiency and excellent in labor saving and productivity can be provided.
(2) Since the gas flow injected from the pulverization nozzle is not easily disturbed, a concentric swirl flow can be maintained in the swirl pulverization chamber without being eccentric even if the pressure of the gas flow is increased to about 15 MPa. The kinetic energy of the pulverized material can be increased as the slag is increased, making it possible to make fine powder by collision between high-energy crushed materials, and easily obtaining metal powder with a sharp particle size distribution in a short time. The manufacturing method of the granular material for shaping | molding which can be provided can be provided.

According to the invention described in claim 5,
(1) The molding granule is crushed and compressed in the mold, and the fine metal powder enters the gaps between the coarse metal powders to fill the gaps. It is possible to provide a method for producing a metal product that can be remarkably improved to 98% and can increase the mechanical strength of the molded body.
(2) Productivity that can reduce man-hours by molding a molding granulated granulated powder and obtaining a molded product, so that a metal product with high mechanical strength can be obtained without sintering. The manufacturing method of the metal product excellent in can be provided.

According to the invention described in claim 6, in addition to the effect of claim 5,
(1) A method for producing a metal product that can increase the mechanical strength of the metal product by sintering in the sintering step can be provided.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a manufacturing flow diagram of a metal product in the first embodiment.
First, a metal material made of aluminum, iron, or an alloy thereof such as stainless steel is prepared. As the metal material, waste generated in the manufacturing process of the metal product by casting or aluminum die casting, for example, a sprue cut and removed is used.
In the washing step, these metal materials are washed using a super mixer or a drum mixer to remove oil on the surface. In the drying step, the metal material is dried to evaporate and remove moisture on the surface.
In the crushing process, the dried metal material is put into a crushing machine such as a cutter mill, a hammer mill, a disk mill, a vibration mill, or a jo crusher to crush.
In the classification process, the crushed metal material is put into a classifier such as a circular sieve or a dry air classifier and classified. Note that the crushed material having a particle size of more than 2000 μm classified in the classification step is again put into a crusher and crushed.

  In the pulverization step, the crushed material of 150 μm to 2000 μm separated in the classification step is put into a pulverizer such as a jet mill and finely pulverized. As the pulverizer, a horizontal swirling jet mill can be used.

Hereinafter, the jet mill used in Embodiment 1 will be described in detail with reference to the drawings.
2 is a cross-sectional view of a main part of the jet mill according to the first embodiment, FIG. 3 is a cross-sectional end view of the main part taken along line AA in FIG. 2, and FIG. 4 (a) is a perspective view of the crushing nozzle. FIG. 4B is a front view of the ejection surface of the crushing nozzle.
In FIG. 2, 1 is the jet mill in the first embodiment, 2 is a swirl crushing chamber formed in a hollow disk shape, 3 is a crushing nozzle provided in seven swirl crushing chambers 2, and 4 is a swirl crushing chamber 2. One supply nozzle for introducing the crushed material into the swirl crushing chamber 2, 4a is a venturi nozzle of the supply nozzle 4, 4b is a solid-gas mixing chamber formed on the upstream side of the venturi nozzle 4a, and 4c is a venturi nozzle 4a. A push nozzle 4d provided coaxially with the venturi nozzle 4a via the solid-gas mixing chamber 4b on the upstream side is a crushing material inlet connected to the solid-gas mixing chamber 4b. The crushing nozzles 3 are arranged at equal intervals on the side wall of the swirling crushing chamber 2 starting from the supply nozzle 4. 5 is a main body casing, 6 is a ring liner of the swirl crushing chamber 2, 7 and 8 are top and bottom liners disposed above and below the swirl crushing chamber 2, and 9 is removably disposed at the center of the bottom liner 8. A center pole having an upper portion formed in a substantially conical shape, 10 is an outlet formed coaxially with the center pole 9 and is detachably disposed on the top liner 7, and 11 is connected to the center upper portion of the swirl crushing chamber 2 and swirled. Fine powder outlet through which the pulverized material crushed in the chamber 2 is discharged, 12 is a high-pressure header, 12a is a high-pressure gas pipe for supplying high-pressure gas from the high-pressure header 12 to the pulverizing nozzle 3, and 12b is from the high-pressure gas header 12 to the supply nozzle 4 A high-pressure gas pipe that supplies high-pressure gas, 13 is a pressure adjustment valve that adjusts the pressure of the high-pressure gas header 12, and 13a is a high-pressure gas pipe that flows through the high-pressure gas pipe 12b. A flow rate adjusting valve for adjusting the flow rate of the gas.

3, 4 (a), and 4 (b), 3 is a crushing nozzle, 3 a is an injection surface of the crushing nozzle 3, and 3 b is formed in a substantially cylindrical shape on the base side of the crushing nozzle 3 and is supplied from a high-pressure header 12. The high pressure gas flow path through which the high pressure gas passes, 3b 'is a slit-shaped high pressure gas flow path formed in a substantially slit shape connected to the high pressure gas flow path 3b, and 3c is opened at the injection surface 3a to open the high pressure gas flow The injection section 3d for injecting the gas flow that has passed through the passage 3b and the slit-shaped high-pressure gas passage 3b ′ has a ratio (aspect ratio) of the length W of the short side to the length L of the long side of W: L = 1. : Slit-shaped injection port 3c of the injection part 3c formed in a substantially rectangular shape of 2 to 1:30, 3e is the central axis of the slit-shaped injection port 3d, 3f is the long side direction through the central axis 3e of the slit-shaped injection port 3d The central axis 3g parallel to the center axis 3g is formed so that the center is located on the central axis 3f. A circular shape injection port.
As shown in FIG. 3, the crushing nozzle 3 includes a crushing nozzle 3 or a supply nozzle 4 in which the central axis 3 e of one crushing nozzle 3 is separated by two in the rotational direction of the swirl flow (counterclockwise in the present embodiment). The swirl crushing chamber 2 is disposed so as to face the central axis.
Here, in Embodiment 1, the inner diameter of the circular injection port 3g is formed to be 1.1 to 3 times the length W of the short side of the slit-shaped injection port 3d.

A method for pulverizing a metal material using the jet mill 1 configured as described above will be described.
When the flow rate adjusting valve 13a is fully opened and the pressure adjusting valve 13 is opened, the high pressure gas is supplied from the high pressure gas pipes 12a and 12b to the pulverizing nozzle 3 and the pushing nozzle 4c of the supply nozzle 4 at the same pressure. Here, an inert gas is used as the high-pressure gas. Thereby, it is possible to prevent an oxide film from being formed on the surface of the metal powder, prevent a decrease in mechanical strength, and prevent a dust explosion.
The metal material of 150 μm to 2000 μm separated in the classification step is supplied from the crushing material inlet 4d and mixed with the inert gas in the solid-gas mixing chamber 4b by the high-pressure jet flow injected from the pushing nozzle 4c, and then from the venturi nozzle 4a. It is supplied to the swirl crushing chamber 2. A swirl flow is generated in the swirl crushing chamber 2 by the high-pressure gas flow injected from the crushing nozzle 3, a crushing zone is formed on the ring liner 6 side of the swirl crushing chamber 2, and a classification zone is formed on the center side of the swirl crushing chamber 2. Is done. In the pulverization zone, the edge-like high-pressure gas flow ejected by the pulverization nozzle 3 is blown into the swirl flow with high shearing properties while maintaining a high speed, and the coarse particles that circulate in the swirl flow are disturbed, and the crushing materials frequently collide with each other. The pulverized material is finely pulverized. The pulverized fine powder is classified in the classification zone and discharged from the outlet 10 disposed in the swirl pulverization chamber 2 through the fine powder discharge port 11. The coarse particles classified in the classification zone and not discharged are swirled on the outer periphery of the swirling flow by centrifugal force generated by swirling, and the coarse particles collide with each other to be repeatedly crushed.
After the swirl flow is formed in the swirl flow forming step, the flow rate of the high-pressure jet flow ejected from the pushing nozzle 4c of the supply nozzle 4 by reducing the opening degree of the flow rate adjusting valve 13a is ejected from the crushing nozzle 3. The flow rate is reduced to about 1/10 to 1/4. In the swirl crushing chamber 2, the high-pressure gas flow forms a concentric swirl flow while maintaining a high speed, and the pulverized material is efficiently crushed in the swirl flow, and the pulverized particles are discharged from the fine powder discharge port 11, According to Bernoulli's theorem, the crushed material is sucked into the swirl crushing chamber 2 even if the flow rate of the high-pressure gas injected from the crushing nozzle 3 is small.

Next, modified examples of the crushing nozzle will be described with reference to the drawings.
FIG. 5 is a front view of a crushing nozzle showing a modified example of the slit-shaped injection port and the circular injection port of the crushing nozzle, and FIG. 6 is a front view showing another modified example of the slit-shaped injection port. FIG. 5A shows an example in which two circular injection ports 3g are formed on both ends of the long side of the slit-shaped injection port 3d, and FIG. 5B shows a circular injection port 3g having a slit-shaped injection. FIG. 5 (c) shows an example in which two circular injection ports 3g are formed at locations excluding both ends of the long side of the slit-shaped injection port 3d. It is an example.
As shown in FIG. 5, the circular injection port 3g can be formed at a plurality of locations as long as the center is formed on the central axis 3f, the size of the inner diameter of the circular injection port, the number, A high-pressure gas stream suitable for pulverization of a wide variety of pulverized materials can be jetted by changing the location to be formed, the aspect ratio of the slit-shaped pulverized portion, and the like.
In FIG. 6, reference numeral 20 denotes a pulverizing nozzle having a slit-shaped injection port 3 d formed therein, and 21 denotes a slit substantially orthogonal to the slit-shaped injection port 3 c over the entire length of the slit-shaped high-pressure gas flow path 3 b ′ of the pulverizing nozzle 20. It is a groove part formed in substantially parallel with the predetermined space | interval W2 on both sides of the long side of 3d shaped injection nozzle. Here, since the width W1 of the groove portion 21 is formed to be 50 to 100 μm, the depth d1 is formed to be 50 to 100 μm, and the interval W2 is formed to be five times W1, the turbulence occurs in the injected gas flow. It is possible to prevent the gas flow rate from decreasing.

As described above, the metal material is finely pulverized by the jet mill 1 and the finely pulverized material is classified and collected by a bag filter or the like connected to the fine powder discharge port 11 so that the average particle diameter is 5.5 μm to 15 μm. A coarse metal powder and a fine metal powder having an average particle size of 0.1 μm to 5 μm can be obtained in high yields.
In the compounding step, the metal fine powder (a) and the metal coarse powder (b) obtained in the pulverization step are a: b = 1 to 40:60 to 99, preferably a: b = 1 to 10 in volume ratio. : Throw in a mill or granulator such as a jet mill at 90 to 99, and collide the metal fine powder with the surface of the metal coarse powder that becomes the core, so that the metal fine powder is pressed into a dotted or film-like shape. Then, the surface of the coarse metal powder is composited by coating (coating) or the like. Note that the mechanical strength of the green compact decreases as the proportion of the metal fine powder in the metal powder (a combination of the metal fine powder and the metal coarse powder) put into the granulator exceeds 10% by volume. It tends to be prominent, and if it exceeds 40% by volume, the tendency becomes remarkable, which is not preferable. In the first embodiment, the above-described jet mill 1 is used in the compounding step.
In the granulation step, the obtained composite powder is put into a granulator such as a rotary pan or a rotary drum, and granulated into a granular material such as a 1 mm to 5 mm pellet. In the granulation step, a binder such as an organic binder or a metal binder can be added. Thereby, a granular material with relatively high strength can be obtained in a short time.

In the molding process, when press molding is performed, the granulated granular material is filled in a cavity of a mold, pressed and compressed, and molded into the shape of a metal product. In press molding, a vibration press apparatus can be used, or hot isostatic pressing (HIP), cold isostatic pressing (CIP), or the like can be used. In the case of press molding, pressure is 5kgf ^/ mm ² ~50kgf ^/ mm 2 is used.
Further, when injection molding such as MIM is performed in the molding process, the molding granular material produced in the granulation process is press-fitted into the cavity of the molding die and injection molded to obtain an intermediate molded body. In the case of injection molding, the heating temperature is about 0.99 ° C., injection pressure 10kgf ^/ mm ² ~90kgf ^/ mm 2 approximately, is used.
In addition, when binders, such as an organic binder, are mixed in a granulation process, it heats at the temperature of 300 to 400 degreeC after shaping | molding, and degreases.
Moreover, the molded object shape | molded by the formation process, especially the intermediate molded object shape | molded by injection molding can be sintered.
In the sintering step, for example, when the metal material is aluminum, sintering is performed at 500 ° C. to 600 ° C. for 1 h to 3 h. When the metal material is tungsten carbide, sintering is performed at 1200 to 1600 ° C. for 1 to 12 hours. In the sintering process, an inert gas atmosphere furnace, a reducing atmosphere furnace, or a vacuum heating furnace is used. Thereby, the mechanical strength of the metal product can be further increased.

Since the metal product manufacturing method according to the first embodiment is configured as described above, it has the following effects.
(1) A metal fine powder having an average particle size of 0.1 μm to 5 μm obtained by pulverizing a metal material with a jet mill or the like is compounded on the surface of a metal coarse powder having an average particle size of 5.5 μm to 15 μm. At the same time, since the composite powder can be granulated into a granular material, when the granular material is filled into a mold and molded, the metal fine powder enters the gaps between the coarse metal powders, and the molded body Can be remarkably improved to 94% to 98%, and the mechanical strength of the molded product can be increased.
(2) In the jet mill 1, the injection unit 3c is provided with the pulverization nozzle 3 provided with the circular injection port 3g in the swirl pulverization chamber 2, or at least a plurality of locations on the long side of the slit-shaped injection port 3d. By providing the groove portions 21 formed substantially parallel to each other with a predetermined interval, it is possible to form a concentric ideal swirl flow in which the swirl flow formed in the swirl crushing chamber 2 is less likely to be eccentric. Thus, it is possible to finely pulverize metal materials made of various metals or alloys, which have been difficult to pulverize until now, and to dramatically increase the processing amount per unit time. In addition, since the eccentricity of the swirl flow and the pressure bonding of the fine powder to the peripheral wall of the swirl crushing chamber 2 are difficult to occur, the peripheral wall and nozzles of the swirl crushing chamber 2 are not easily worn, and there is little contamination and more stable continuous operation is performed. be able to.
(3) Further, since the gas flow injected from the crushing nozzle 3 is not easily disturbed, a concentric swirl flow can be maintained in the swirl crushing chamber 2 without being eccentric even if the pressure of the gas flow is increased to about 15 MPa. As the gas flow pressure is increased, the kinetic energy of the pulverized material can be increased, and it is possible to make fine powder by collision between high energy crushed materials. Can get to.
(4) By granulating into a granular material having a particle size of 1 mm to 5 mm in the granulation step, it becomes easy to carry in and out in the subsequent step, and particularly when the mold is filled in the molding step, etc. There is no problem that the metal powder enters between the female molds, and the handling property can be improved.
(5) A molded article can be obtained by filling the molding granule into a mold and molding it using press molding, injection molding or the like. At this time, the molding granular material is crushed and compressed in the molding die, and the metal fine powder enters the gaps between the coarse metal powders to fill the gaps. It can be remarkably improved to 98%, and the mechanical strength of the molded body can be increased.
(6) When the molded body is sintered after molding, a product with a small shrinkage rate of the molded body due to sintering and high dimensional accuracy can be obtained, and a product with high sintered density and excellent mechanical strength can be obtained. Can be obtained. In addition, by molding a molding granulated granulated composite powder to obtain a molded body, a metal product with high mechanical strength can be obtained without sintering.

(Example 1)
A metal material made of aluminum (pouring gate and the like cut and removed in the metal product manufacturing process) was pulverized by a jet mill, and then classified and collected by a bag filter to obtain aluminum powder. The aluminum powder was collected, and the particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring apparatus (CILAS 1064, manufactured by Cirrus), and observed with a scanning electron microscope (SEM). The average particle size of the measured particle size distribution was 7 μm. FIG. 7 is a photograph of pulverized aluminum powder using SEM.
Further, a high pressure gas of 0.88 MPa is supplied to one jet mill supply nozzle and seven pulverization nozzles described in the first embodiment, a metal material made of cobalt is supplied as a pulverizer, and pulverized to obtain cobalt powder. It was. The cobalt powder was recovered, and the particle size distribution was measured in the same manner as the aluminum powder, and observed with an SEM. The average particle size of the measured particle size distribution was 0.8 μm. FIG. 8 is a photograph of pulverized cobalt powder using SEM.
The obtained cobalt powder (fine metal powder) and aluminum powder (coarse metal powder) were introduced into a jet mill at a volume ratio of 10:90, and the surface of the aluminum powder was coated with cobalt powder. This was put into a granulator such as a rotary pan or a rotary drum, and an organic binder was added to granulate into pellets of 1 mm to 5 mm.
The granulated granule was filled into a mold cavity, pressed and compressed, and pressed into a metal product shape. Applied pressure with ^{5kgf / mm 2 ~50kgf / mm 2} . After forming and degreasing by heating at a temperature of 300 ° C. to 400 ° C., sintering was performed at 500 ° C. to 600 ° C. to obtain a predetermined metal product.
Similarly, when a plurality of metal products were produced and the relative density of these metal products was measured, all of them were extremely high in the range of 94% to 98%. The relative density was measured according to JIS Z2505.

(Comparative Example 1)
In the same manner as in Example 1, except that a granular material obtained by granulating a metal powder having an average particle diameter of 10 μm to 30 μm manufactured by a gas atomizing method instead of the metal coarse powder and the metal fine powder was used. Got a metal product. When the relative density of these metal products was measured by the same measurement method as in Example 1, all were 78% to 80%.

  From the results of Example 1 and Comparative Example 1, it was determined that the metal fine powder having an average particle diameter of 0.1 μm to 5 μm was pressed on the surface of the metal coarse powder having an average particle diameter of 5.5 μm to 15 μm to form a composite. It has been found that the relative density of the compact can be significantly improved because fine metal powder enters the gaps between the coarse metal powders during molding and fills the gaps.

As described above, the present invention relates to a composite powder for molding a metal product used when molding a metal product by press molding, injection molding, or the like. In particular, according to the present invention, the relative density of the molded body is significantly improved. Therefore, it is possible to provide a composite powder for molding a metal product, which can increase the mechanical strength of the molded body and can obtain a product with high dimensional accuracy.
The present invention also relates to a method for producing a molding granular material used when molding a metal product by press molding, injection molding, or the like. In particular, according to the present invention, it is not necessary in a stamped metal waste material, a gas atomizing method, or the like. In addition, waste materials with a relatively large particle size can be made into fine powder by a simple process using a jet mill, so that they are excellent in labor and cost savings and excellent in productivity, and when metal products are formed by press molding or injection molding. The manufacturing method of the granular material for shaping | molding which it is easy to handle and is used suitably can be provided.
In addition, the present invention relates to a method for producing a metal product using a granular material for molding, and in particular, according to the present invention, a waste metal having a relatively large particle diameter, which has been made unnecessary by a stamped metal waste material or a gas atomizing method, etc. Since it can be made into fine powder by simple processing using a jet mill, it is excellent in labor-saving and cost-saving, and it is excellent in productivity, and the compacted green compact can be densified and mechanical strength is free from cracks and cracks. It is possible to provide a method for producing a metal product that can provide a metal product that is excellent in the quality.

Manufacturing flow diagram of metal product in Embodiment 1 Cross section of the main part of the jet mill 2 is a cross-sectional end view of the main part taken along line AA in FIG. (A) Perspective view of grinding nozzle (b) Front view of ejection surface of grinding nozzle Front view of the crushing nozzle showing a modification of the slit-shaped nozzle and the circular nozzle Front view showing another modification of the slit-shaped injection port Photo of ground aluminum powder using SEM Photograph of pulverized cobalt powder using SEM

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Jet mill 2 Swivel crushing chamber 3 Grinding nozzle 3a Injection surface 3b High pressure gas flow path 3b 'Slit high pressure gas flow path 3c Injection part 3d Slit injection port 3e Central axis 3f Center axis 3g Circular injection port 4 Supply nozzle 4a Venturi Nozzle 4b Solid gas mixing chamber 4c Push nozzle 4d Crushed material inlet 5 Body casing 6 Ring liner 7 Top liner 8 Bottom liner 9 Center pole 10 Outlet 11 Fine powder outlet 12 High pressure header 12a, 12b High pressure gas pipe 13 Pressure adjustment valve 13a Flow rate adjustment Valve 20 Grinding nozzle 21 Groove

Claims (6)

  A composite powder for molding a metal product, characterized in that a metal fine powder having an average particle size of 0.1 to 5 μm is pressed onto a surface of a coarse metal powder having an average particle size of 5.5 to 15 μm to form a composite. A pulverization step of pulverizing a metal material to obtain a metal fine powder having an average particle size of 0.1 μm to 5 μm;
A compounding step of compounding the metal fine powder on the surface of a metal coarse powder having an average particle size of 5.5 μm to 15 μm;
A granulation step of granulating the composite powder obtained in the composite step into a granular material having a particle size of 1 mm to 5 mm;
The manufacturing method of the granular material for shaping | molding characterized by the above-mentioned.   The method for producing a granular material for molding according to claim 2, wherein the metal material is pulverized in an inert gas atmosphere in the pulverization step. In the pulverizing step, a method for producing a molding granule for pulverizing the metal material using a horizontal swirling jet mill,
The pulverizing nozzle that forms the swirl flow of the jet mill includes an injection unit that injects gas, and the injection unit has a slit-shaped injection port formed in a slit shape, and a central axis that passes through the central axis of the slit-shaped injection port One or more circular injection ports formed so that the center is positioned on a line, the slit injection port, and a slit-shaped high-pressure gas channel communicating with the circular injection port, The manufacturing method of the granular material for shaping | molding of Claim 2 or 3 to do.   A method for producing a metal product, comprising filling a molding die with the molding granule obtained by the method for producing a molding granule according to any one of claims 2 to 4. The method for producing a metal product according to claim 5, further comprising a sintering step of sintering the formed body formed in the forming step.