JP6549435B2 - Method of manufacturing powder pressed compact - Google Patents

Description

  The present invention relates to a method for producing a molded body by press-forming metal or ceramic raw material powder using a resin-made mold made by an optical forming method, a three-dimensional (3D) printer or the like.

  The powder press molding method is a method in which raw material powders such as metal powder and ceramic powder are put into a mold using a powder press molding apparatus and pressed into a desired product shape by applying a predetermined pressure. After press-molding, the compact can be sintered at a predetermined temperature to obtain a product. The powder press molding apparatus usually comprises a press molding machine body, a die set and a mold. The powder press molding machine main body has an upper ram for pressing and a lower ram for demolding, and a die consisting of an upper punch, a lower punch, a die and a core is attached to a die set, Filling, molding and demolding are performed automatically.

  In the past, molds for powder press forming devices generally require durability such as wear resistance, impact resistance, chipping resistance, etc., and tool steels such as cemented carbide, cast iron, cast steel, forged steel, etc. are used ( See, for example, Patent Documents 1 and 2.).

  On the other hand, as a mold used for injection molding, foam molding, RIM molding, casting, vacuum casting, vacuum molding, RTM molding, powder molding, blow molding, compression molding, press molding, extrusion molding, FRP molding, lamination molding method The mold produced by these is disclosed (for example, refer patent document 3). The patent document 3 describes that the mold is superior in strength, wear resistance, durability and releasability to conventional molds and can shorten the time for manufacturing the mold. . This mold is manufactured by a lamination molding method using a composite material powder containing spherical carbon and a resin powder as essential components.

JP 2005-152961 A (paragraphs [0002], [0004]) Unexamined-Japanese-Patent No. 2004-306119 (Paragraph [0023]) JP, 2010-234800, A (summary, claim 1, paragraph [0001])

  In the case of producing a shaped body of complex shape with a mold using a tool steel shown in Patent Documents 1 and 2, it takes a large number of production days and cost to produce the mold and produces a mass-produced product. In the previous step, it was not possible to manufacture a prototype by this press molding method from the viewpoint of production days and production cost. In the case of using a composite material powder in which a metal material, a ceramic material and a resin are mixed, using a carbon material shown in Patent Document 3 as a starting material and manufacturing a resin mold by a lamination molding method, the above tool steel is used. While the problem of the mold is solved, the resin mold having increased strength or heat resistance has complicated setting of the compounding ratio for obtaining appropriate strength or heat resistance, and the raw material and manufacturing cost thereof are increased. There was a problem. Moreover, when powder press molding is performed using this kind of resin mold, the press pressure can not be higher than the press pressure by the die using tool steel, and it exists inside the molded body when it is made into a sintered product There was weakness in strength due to the holes.

  The first object of the present invention is to use a resin mold made of a photocurable resin which does not contain a material other than a resin which is three-dimensionally shaped using an optical shaping method or a three-dimensional printer. It is an object of the present invention to provide a method for easily and inexpensively producing a powder press molding without chipping. A second object of the present invention is to provide a method for producing powder press compacts of a plurality of shapes of the same shape and size without damaging the resin molding die structurally even if the molded articles are repeatedly produced. is there. Further, a third object of the present invention is to produce a powder press-formed body having a strength which is not inferior to that of a sintered body of a formed body press-formed by a die using tool steel when made into a sintered article. To provide a way to

  The present inventors replaced the resin molding die by the lamination molding method using the composite material powder in which the carbon material, the metal material, and the ceramic material and the resin are mixed, a material other than the resin by the optical molding method or the three-dimensional printer A resin mold made of a photocurable resin not containing any of the above, and on the other hand, spherical granulated powder having a particle size (D50) of 50 to 200 μm and containing 3 to 12% by mass of a binder as raw material powder If press molding is repeatedly performed at a pressure of 50 to 300 MPa and a press temperature lower than the heat resistance temperature of the resin mold, predetermined dimensions without cracks, flaws and chips are obtained without structurally damaging the resin mold. It is possible to easily and inexpensively produce a plurality of powder press compacts of the same shape and size as usual, and when sintered into a sintered product, it is inferior in strength to a sintered product of a powder press compact made with a conventional mold. Focusing on the absence, we have reached the present invention.

  According to a first aspect of the present invention, there is provided a method for producing a powder pressed compact by pressing raw material powder filled in a die cavity formed by a lower punch and a die between the lower punch and the upper punch. The mold comprising the lower punch, the upper punch and the die is a resin mold comprising a photocurable resin which does not contain a material other than a resin three-dimensionally shaped using an optical shaping method or a three-dimensional printer, The raw material powder is a spherical granulated powder having a particle size (D50) of 50 to 200 μm obtained by mixing a metal powder or ceramic powder and a binder, and the binder is contained in 100% by mass of the granulated powder. And 12 mass%, powder press molding characterized in that the press molding of the granulated powder is performed at a press pressure of 50 to 300 MPa and a press temperature not higher than the heat resistance temperature of the resin mold. It is a method of manufacture.

  A second aspect of the present invention is the invention based on the first aspect, wherein the metal powder is iron powder, Ni powder, Co powder or a mixed powder thereof, alloy steel powder, stainless steel powder, corrosion resistant alloy powder Or magnetic alloy powder.

A third aspect of the present invention is the invention based on the first aspect, wherein the ceramic powder is zirconia (ZrO ₂ ) powder, alumina (Al ₂ O ₃ ) powder or aluminum nitride (AlN) powder. It is characterized by

  A fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the binder is polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) Or polyethylene glycol (PEG), or any combination thereof.

  A fifth aspect of the present invention is a method for producing a sintered product by sintering a powder press-molded product produced by the method according to any one of the first to fourth aspects.

  In the method of producing a powder press molded article according to the first aspect of the present invention, powder is produced using a resin mold made of a photocurable resin which does not contain a material other than a resin produced by an optical forming method or a three-dimensional printer. In order to manufacture a press-formed product, it is manufactured by a lamination molding method using an expensive mold and a carbon material, a metal material, and a composite material powder in which a ceramic material and a resin are mixed by conventional machining and the like. As compared with the conventional resin mold, the molded body can be manufactured simply and inexpensively. In particular, in the case of a stereolithography method or a three-dimensional printer, even if the shape of the required product is complicated and fine, the shape of the resin mold can be created faithfully and precisely conforming to the shape. In addition, a binder is contained at 3 to 12% by mass, and a spherical granulated powder having a powder particle size (D50) of 50 to 200 μm is used as a raw material powder, at a pressure of 50 to 300 MPa and a pressing temperature lower than the heat resistance temperature of the resin mold By performing press molding, even if it is a resin mold made of a single kind of resin, this resin mold is elastically deformed at the time of pressing and returns to the original form after pressure release, so the resin mold is structured It is possible to carry out repeated molding without damaging it. As a result, a plurality of powder compacts of the same shape and size can be manufactured without cracks, scratches and chips. In the conventional press molding using a metal mold etc., a large pressing pressure is required when producing a green compact having a shape maintained by crushing metal powder etc. By pressing and forming a compact as a green compact at a low temperature without collapsing metal powder and the like, and sintering the powder press compact, a sintered product which does not decrease in strength can be obtained. This makes it possible to easily manufacture powder press moldings for trial products such as toys, daily goods, automobile parts, and electric parts.

  The method for producing a powder pressed compact according to the second aspect of the present invention is a metal powder of iron powder, Ni powder, Co powder or a mixture thereof, alloy steel powder, stainless steel powder, corrosion resistant alloy powder, or magnetic alloy powder. By using as raw material powder, various metal-made molded objects can be manufactured.

The method for producing a powder pressed compact according to the third aspect of the present invention uses ceramic powder of zirconia (ZrO ₂ ) powder, alumina (Al ₂ O ₃ ) powder or aluminum nitride (AlN) powder as raw material powder. Various ceramic moldings can be produced.

  In the method of producing a powder press-molded product according to the fourth aspect of the present invention, water solubility of polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) or polyethylene glycol (PEG) or a combination thereof is used. The binder of Thus, the aqueous binder solution and the metal powder or ceramic powder can be mixed and slurried to produce a desired granulated powder of the metal powder or ceramic powder. In addition, the powder properties of the granulated powder are improved, and when the powder press compact is sintered, it is easily degreased.

  According to the method of the fifth aspect of the present invention, the sintered product is produced by sintering the powder press-molded product produced by the method according to any one of the first to fourth aspects, thereby producing a sintered product. It is possible to manufacture a metal or ceramic sintered product having a small variation in size and shape, and a strength equal to that of a sintered product of a powder press molded product using a conventional mold.

It is a block diagram of the apparatus which manufactures the powder press molded object which concerns on embodiment of this invention. FIG. 1 (a) shows a state in which the raw material powder is filled in the die cavity, and FIG. 1 (b) shows a state in which the raw material powder is press-formed between the upper and lower punches. It is a figure which shows the condition before filling raw material powder | flour in the die cavity concerning embodiment of this invention. It is an external appearance perspective view of the powder press molded object manufactured by embodiment of this invention. It is a schematic sectional drawing which shows the optical lamination molding method for manufacturing the lower punch which concerns on embodiment of this invention. FIG. 4 (a) shows a state in which the first cured thin layer having a predetermined shape is formed, and FIG. 4 (b) shows a state in which the table is moved slightly downward to form a second cured thin layer. FIG. 4C shows a state in which the lower punch, which is a photofabricated object having a predetermined three-dimensional shape, is formed. The sintered product obtained by the Example and the comparative example is shown. 5 (a) shows its plan view, and FIG. 5 (b) shows its side view. It is a figure which shows the bending test of the sintered product obtained by the Example.

  Next, an embodiment of the present invention will be described with reference to the drawings.

[Method of producing granulated powder as raw material powder]
First, a method of producing granulated powder, which is a raw material powder for producing a powder pressed compact, will be described. The raw material powder of this embodiment is a granulated powder obtained by mixing a metal powder or a ceramic powder with a binder. Examples of the metal powder include iron powder, Ni powder, Co powder or mixed powder thereof, alloy steel powder, stainless steel powder, corrosion resistant alloy powder, magnetic alloy powder and the like. In particular, as stainless steel powder, SUS316L, SUS630, SKD11, SKH57, etc. are exemplified. Further, examples of the ceramic powder include zirconia (ZrO ₂ ) powder, alumina (Al ₂ O ₃ ) powder, aluminum nitride (AlN) powder and the like. The powder particle size (D50) of the metal powder or ceramic powder is preferably 20 μm or less. Furthermore, 10 micrometers or less are more preferable. With metal powder or ceramic powder having a particle size of more than 20 μm, when formed into a press-formed product under pressure described later, pores are formed between the powders, and pores remain during sintering in a later step, resulting in a sintered product Density and strength tend to decrease. In the present specification, the powder particle size (D50) refers to the median value of the particle distribution (diameter) measured by a laser diffraction scattering particle distribution measuring apparatus (model name: HORIBA LA-950) three times. Average value.

  Examples of the binder include polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and polyethylene glycol (PEG), or a water-soluble binder in combination thereof. The said binder plays the role of the glue which aggregates powder of metal powder or ceramic powder. The aqueous binder solution and metal powder or ceramic powder can be mixed and slurried to produce the desired granulated powder of metal powder or ceramic powder. In addition, when a granulated powder is produced with this binder, the green powder characteristics of the granulated powder are improved, and furthermore, it is easy to degrease when the powder press compact is sintered.

  In order to produce granulated powder, first, the binder is dissolved in pure water to form an aqueous solution, and the metal powder or ceramic powder and a binder aqueous solution are mixed to form a slurry in which the metal powder or ceramic powder is uniformly dispersed. Here, in the slurry, the binder is contained in an amount of 3 to 12% by mass, preferably 5 to 8% by mass. If it is less than 3% by mass, the powder particle size (D50) of the granulated powder to be produced is too small, and if it exceeds 12% by mass, the powder particle size (D50) of the granulated powder to be produced becomes too large. When the hardness of the metal powder or ceramic powder to be used is high, or when the powder particle size (D50) thereof is small, it is preferable that the binder be contained in a large amount within the above range.

  The granulation apparatus of the present embodiment is configured as follows. A slurry tank for storing the above-mentioned slurry is disposed at the upper center of the inverted truncated cone-like cylinder, a rotating disc is horizontally disposed at the upper center of the cylinder, and hot air is directed toward the cylinder at the upper portion of the cylinder. A blow-out dryer is placed. The lower end (conical tip) of the inverted frusto-conical tube is open, and a granulated powder collection container is disposed below the lower end. In order to produce granulated powder, a horizontally arranged disc is rotated at a speed of 10000 to 20000 rpm, and a slurry is dropped from the slurry tank at a rate of 300 to 500 kg / h onto the rotating disc. The fine droplets of the slurry spattered from the disk become spherical granulated powder which is powder particles which are dried and aggregated by removing water by hot air from a dryer in a cylinder. The spherical granulated powder travels along the conical portion of the inverted truncated cone-like cylinder by its own weight, falls to the lower end of the cylinder, and enters the collection container from the lower opening of the cylinder.

  The granulated powder produced by the above method is a spherical powder having a powder particle size (D50) of 50 to 200 μm. This powder particle size (D50) is obtained by adjusting the above-mentioned binder concentration, the amount of dripping of the slurry per unit time, and the rotational speed of the disk. The powder particle size (D50) of the spherical granulated powder is preferably 80 to 100 μm. The spherical granulated powder is excellent in fluidity into a mold including an upper punch, a lower punch and a die described later. When the powder particle size (D50) of the granulated powder is less than 50 μm, the granulated powder is ejected from the clearance of the molding die, and a desired press-formed product can not be obtained. Also, if it exceeds 200 μm, when the granulated powder is filled in the molding die, the granulated powder is not filled in the fine part or it is difficult to fill the necessary and sufficient amount of granulated powder in the molding die As a result, pores remain between the granulated powders, and a press-formed product having a desired shape or a desired density can not be obtained. The spherical granulated powder in the above powder particle size (D50) range is three-dimensionally shaped using a stereolithography method or a three-dimensional printer, and even if the forming die is complicated, every corner in the forming die Granulated powder can be distributed to the end, and the formability of the powder press compact described later can be improved.

[Method for producing powder press compact]
Next, the method to manufacture a powder press molding using the granulated powder obtained by the said method is demonstrated. First, an apparatus for producing a powder press compact according to an embodiment of the present invention (hereinafter referred to as a powder press compacting apparatus) will be described. As shown in FIG. 2, the powder press molding apparatus 10 according to the present embodiment supplies powder in a die cavity 14 formed by a die 12 attached to a die plate 11 and a lower punch 13 fitted to the die. A device for filling granulated powder M which is a raw material powder from 20 and compacting the granulated powder M in the die 12 between the upper punch 15 and the lower punch 13 as shown in FIGS. 1 (a) and 1 (b) It is. The powder feeding apparatus 20 shown in FIG. 2 is configured by connecting a hopper 16 provided at a high position for storing granulated powder which is raw material powder and a box-like feeder 17 without a bottom by a flexible hose 18. Ru. The feeder 17 advances from the standby position shown in FIG. 2 toward the die (left direction in the figure) from the standby position shown in FIG. 2 by the drive rod 19 of the actuator, reaches the top of the die 12 and mixes granulated powder as raw material powder into the die cavity 14. Then, the granulated powder which is the raw material powder poured into the die is retracted to the standby position while the upper surface is flattened at the lower edge of the feeder 17 to complete one cycle of filling.

  As shown in FIGS. 1A and 1B, the lower punch 13 of the powder press molding apparatus 10 is fixed to a base 22 via a ground plate 21. The die plate 11 to which the die 12 is attached is supported by the column plate 24 via the column 23 penetrating the ground plate 21, and the column plate 24 is attached to the lower ram 26.

  In the powder press molding apparatus 10 configured as described above, the die 12 simultaneously moves up and down as the lower ram 26 moves up and down. As shown in FIG. 1A, the upper punch 15 is lowered to be fitted into the die cavity 14 with respect to the die 12 in a state where the granulated powder M, which is the raw material powder, is filled in the die cavity 14 and raised. Then, the granulated powder which is the raw material powder is compressed. As shown in FIG. 1 (b), the granulated powder which is the raw material powder is compressed by the upper punch 15, and the lower punch 13 is raised to further compress the granulated powder which is the raw material powder. By pressing the granulated powder which is the raw material powder by the upper punch 15 and the lower punch 13, a powder press compact P shown in FIG. 3 which is a green body (green compact) is formed.

  The press molding pressure when forming the powder press compact P is 50 to 300 MPa, preferably 100 to 200 MPa. When the press molding pressure is less than 50 MPa, the granulated powder is difficult to be broken or deformed by the press molding pressure, and a void remains in the powder press compact, and the density of the sintered product is obtained even if this powder press compact is sintered And the strength can not be increased. In addition, when the press molding pressure exceeds 200 MPa, a resin mold to be described later is worn at the time of pressing, or cracks or cracks occur. Further, it is not necessary to heat the press molding temperature specially in this embodiment to raise the temperature. The temperature of the resin mold due to the frictional heat of the granulated powder when repeatedly press-formed, the frictional heat when pushing the powder press compact from the mold, etc. may be equal to or less than the heat resistance temperature of the resin mold.

  The mold consisting of the die 12, the lower punch 13 and the upper punch 15 of the present embodiment is a resin mold and is three-dimensionally shaped using an optical forming method or a three-dimensional printer. In the present embodiment, a resin-made mold, which is an optically shaped article, is manufactured by an optical three-dimensional modeling method represented by an optical layered modeling method. FIGS. 4A to 4C show steps of forming the lower punch 13 by the optical additive manufacturing method. Three-dimensional data of a shaped object corresponding to the lower punch 13 is obtained in advance, and the data is divided into circular slices at equal intervals in calculation and stored as slice data. As shown in FIG. 4A, in the liquid tank of the container 32 containing the liquid photocurable composition 31, it moves in the vertical direction so that the upper surface is positioned downward by a slight distance from the liquid surface 33. Arrange the possible tables 34. The liquid photocurable composition contains a radically polymerizable compound such as a (meth) acrylic monomer, a polymerizable monomer containing a cationically polymerizable compound such as an epoxy compound, a photopolymerization initiator, and the like. After arranging the table 34, the thin layer of the liquid photocurable composition 31 on the table 34 is scanned with the ultraviolet laser light 37 from the ultraviolet laser device 36 in a predetermined pattern based on the stored data, The first cured thin layer 13a having a predetermined shape is formed. Then, as shown in FIG. 4B, the thin layer of the liquid photocurable composition 31 is placed on the first cured thin layer 13a by moving the position of the table 34 downward by a slight distance. After forming, the thin layer is scanned in a predetermined pattern based on the stored data based on the ultraviolet laser light 37 to form a second hardened thin layer 13b having a predetermined shape. Thereafter, the same operation is repeated, and finally, as shown in FIG. 4C, photofabrication having a predetermined three-dimensional shape which is an aggregate of a plurality of cured thin layers 13a, 13b,. The lower punch 13 is obtained. Although not shown, the upper punch and the die are also manufactured in the same manner as the lower punch 13.

  In addition, the resin mold which is the shaped article of the present invention is not limited to the above-described photo-stacking method, but an inkjet ultraviolet curing method using an acrylic photo-curing resin by a three-dimensional printer, an ABS resin (acrylonitrile -It may manufacture by the thing of the hot melt lamination system using a butadiene styrene copolymer synthetic resin), and the thing of the powder fixation system using a powder. Further, the resin mold of the present invention includes any material for the purpose of making the strength or heat resistance of a carbon material, a metal material, a ceramic material, etc. closer to a conventional mold from the viewpoint of materials, ie, materials other than resin. Not. Therefore, the heat resistance temperature of the resin mold of the present invention, which depends on the material of the raw material resin, is in the range of 70 to 100 ° C. In the present specification, “heat-resistant temperature of resin-made mold” means that the material constituting the resin-made mold does not deteriorate, such as decomposition or dissolution, and maintains a structure equivalent to the structure at room temperature (25 ° C.) Say the highest temperature. Furthermore, the resin mold of the powder press molding apparatus of the present invention includes one comprising a die, a lower punch, an upper punch and a core.

[Method of producing sintered product]
Next, a method of producing a sintered product using the powder press compact P obtained by the above method will be described. First, degreasing of the powder press compact is performed. In the degreasing step, the binder contained in the powder press compact is removed. For example, the powder pressed compact is heat treated in the air and in a nonoxidizing atmosphere such as nitrogen gas at a temperature of 200 to 500 ° C. for 2 to 8 hours.

  Subsequently, the degreased powder press compact is heated to 1000 to 1500 ° C. under ordinary sintering conditions, for example, in a non-oxidizing atmosphere such as nitrogen gas in the atmosphere, and the temperature is maintained for 0.5 to 8 hours. Hold and bake. Thereby, a sintered product is obtained. Degreasing and sintering may be performed in separate heating furnaces or in the same heating furnace.

  Next, an example of the present invention will be described in detail along with a comparative example.

<Production example of granulated powder>
As shown in Table 1, granulated powder (No. 1 to No. 6) prepared by mixing SUS316L which is stainless steel powder and PVA which is a binder, and zirconia (ZrO ₂ ) powder which is ceramic powder and a binder Seven types of granulated powders were prepared using granulated powder (No. 7) mixed with CMC as a raw material powder. The powder particle sizes (D50) of stainless steel powders No. 1 to No. 6 were all 7 μm, and the powder particle size (D50) of zirconia powders No. 7 was 0.09 μm. The powder particle size (D50) of the granulated powder of No. 1 to No. 6 was adjusted to 45 to 210 μm by changing the content of CMC of the binder. Moreover, the powder particle size (D50) of the granulated powder of No. 7 was prepared at 80 micrometers.

<Production example of molding die>
First, a molding die composed of a lower punch, an upper punch, and a die made of an ultraviolet curable resin, which were respectively shaped by a three-dimensional printer, was prepared. Here, as shown in FIGS. 5 (a) and 5 (b), a dumbbell-shaped test piece S (thickness 3.5 mm, parallel portion width 6 mm, parallel portion length 30 mm, shoulder portion according to No. 14 of JIS Z 2201 The mold was manufactured so that a radius of 20 R, a grip width of 10 mm, and a total length of 100 mm) were obtained as a sintered product.

Example 1
Granulated powder containing No. 3 SUS316L stainless steel powder shown in Table 1 is filled in a molding die of a powder press molding apparatus, and powder press molding is carried out under powder press molding conditions at room temperature under a press molding pressure of 50 MPa shown in Table 2. did. The compact is degreased by holding it at a temperature of 320 ° C. for 120 minutes in a nitrogen gas atmosphere, and subsequently the degreased compact is held at a temperature of 1300 ° C. for 120 minutes in a nitrogen gas atmosphere and sintered as shown in FIG. I got the goods.

Example 2
Granulated powder containing SUS316L No. 2 stainless steel powder shown in Table 1 is filled in the same molding die of the powder press molding apparatus as in Example 1 and the press molding pressure is 100 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Example 3
Granulated powder containing No. 3 SUS316L stainless steel powder shown in Table 1 is filled in the same molding die of the powder press molding apparatus as in Example 1 and the press molding pressure is 100 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Example 4
Granulated powder containing No. 4 SUS316L stainless steel powder shown in Table 1 is filled in the same molding die of the powder press molding apparatus as in Example 1 and the press molding pressure is 100 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Example 5
Granulated powder containing SUS316L stainless steel powder of No. 5 shown in Table 1 is filled in the same mold of the powder press molding apparatus as in Example 1 and the press molding pressure is 100 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Example 6
Granulated powder containing SUS316L stainless steel powder of No. 3 shown in Table 1 was filled in the same molding die of the powder press molding apparatus as in Example 1 and the press molding pressure was 200 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Comparative Example 1
Granulated powder containing SUS316L No. 1 stainless steel powder shown in Table 1 was filled into the same molding die of the powder press molding apparatus as in Example 1 and molded with a press molding pressure of 100 MPa. The amount of binder was 2 mass Because the particle size (D50) of the granulated powder was as small as 45%, the molded product having the desired shape could not be produced, and degreasing and sintering were not performed.

Comparative Example 2
Granulated powder containing SUS316L stainless steel powder No. 3 shown in Table 1 is filled into the same molding die of the powder press molding apparatus as in Example 1 and molded with a press molding pressure of 45 MPa, and the molding pressure is 45 MPa. Because of the low temperature, it was not possible to produce a shaped body having the desired shape, and degreasing and sintering were not performed.

Comparative Example 3
Granulated powder containing SUS316L stainless steel powder No. 3 shown in Table 1 is filled into the same molding die of the powder press molding apparatus as in Example 1 and molded with a press molding pressure of 210 MPa, and the molding pressure is 210 MPa. Since it was high, the lower and upper punches were broken and could not be molded. For this reason, neither degreasing nor sintering was possible.

Comparative Example 4
Granulated powder containing SUS316L stainless steel powder of No. 6 shown in Table 1 is filled in the same mold of the powder press molding apparatus as in Example 1 and the press molding pressure is 100 MPa, under the same conditions as in Example 1 It was pressed, degreased and sintered to obtain a sintered product.

Reference Example 1
The same powder press forming apparatus as in Example 1, but using a mold in which the lower and upper punches and the upper punch and the die are made of tool steel, and including the No. 3 SUS316L stainless steel powder shown in Table 1 The granular powder was filled in a mold and press-formed at room temperature under a press-forming pressure of 300 MPa. The molded compact was degreased and sintered under the same conditions as in Example 1 to obtain a sintered product.

Example 7
Granulated powder containing zirconia powder No. 7 shown in Table 1 was filled in the same mold of the powder press molding apparatus as in Example 1 and powder shown in Table 2 was used under powder press molding conditions of 200 MPa pressure and room temperature. Press molded. The compact is degreased by holding it at a temperature of 500 ° C. for 120 minutes in a nitrogen gas atmosphere, and subsequently the degreased compact is held at a temperature of 1450 ° C. for 120 minutes in a nitrogen gas atmosphere and the sintering shown in FIG. I got the goods.

<Comparison result 1 (presence of damage to press evaluation and mold)>
In order to confirm whether or not the shape is maintained after molding, the presence or absence of cracks, flaws, and chips was visually determined for the molded articles press-molded in Examples 1 to 7 and Comparative Examples 1 to 4 and Reference Example 1. Furthermore, the presence or absence of each breakage of the upper punch, the lower punch and the die was visually determined. The results are shown in Table 3.

<Comparison result 2 (Evaluation of sintered products)>
With respect to the sintered products of SUS316L obtained in Examples 1 to 7 and Comparative Example 4 and Reference Example 1, the relative density to the theoretical density (100%) is determined by the Archimedes method, and Examples 1 to 6 and Reference The dumbbell-shaped test pieces according to JIS Z 2201 No. 14, which is a sintered product of SUS 316 L of Example 1, were measured for tensile strength at room temperature according to JIS Z 2241 (2011) (Metal Material Tensile Test Method). The results are shown in Table 3. Further, as shown in FIG. 6, the dumbbell-shaped test piece S, which is a sintered product of the zirconia powder of Example 7, is placed on two supporting points 41, 41 having a distance of 20 mm between supporting points on the substrate 40; A load was applied to a position T corresponding to the center of the fulcrum 41 at a speed of 1 mm / min at room temperature, and a three-point bending test was performed to measure its bending strength. The bending strength is the value of stress when the bending load is maximum. The results are shown in Table 4.

  As apparent from Table 3, in Reference Example 1 in which a mold was used as the mold, the moldability was naturally good and there was no mold breakage. As described above, in Comparative Examples 1 and 2, although there was no breakage of the mold, it was not possible to produce a molded body having a desired shape. Further, in Comparative Example 3, the forming die (upper and lower punches) was broken and the forming itself could not be performed. On the other hand, in Examples 1 to 6 and Comparative Example 4, a molded body having a desired shape could be produced, and there was no breakage of the mold. Regarding the relative density and the tensile strength, the relative density of the sintered product of SUS316L obtained in Reference Example 1 was as high as 97%, and the tensile strength was also as high as 520 MPa. On the other hand, the relative density of the sintered product of SUS316L obtained in Comparative Example 4 was 89% lower than that of Reference Example 1, and the tensile strength was also lower than that of Reference Example 1, 404 MPa. The reason for this is that the granulated powder of Comparative Example 4 had a high binder content of 13% by mass and the powder particle size (D50) of the granulated powder was 210 μm, so it was estimated that the pores remained in the powder press compact . The relative density of the sintered product of SUS316L obtained in Examples 1 to 6 is 93 to 96%, which is slightly lower than that of Reference Example 1, and the tensile strength of these is also 451 to 497 MPa. The tensile strength was about the same. From this, it was found that the sintered products of Examples 1 to 6 were comparable in density and strength to sintered products made from powder press-formed products using conventional molds. Further, as apparent from Table 4, the relative density of the sintered product produced from the zirconia powder obtained in Example 7 was 99% as in Reference Example 1, and the flexural strength was 832 MPa.

<Comparison result 3 (repetitive press formability evaluation)>
The same powder press molding apparatus as in Example 1 is used, and the same granulated powder as in Example 1 is filled in a mold consisting of an upper punch, a lower punch and a die identical to that in Example 1, and powder press molding is repeated The After 100 times of powder press molding, cracks, flaws, chips and the like were visually inspected for the upper punch, the lower punch and the die. Further, the presence or absence of cracks, flaws and chipping of 100 pressed articles was visually determined. Moreover, it was visually judged whether the molded object was press-formed according to the predetermined dimension. As a result, the upper punch, the lower punch and the die had the same appearance as that after the first press molding, and there were no cracks, flaws and chips. This is also demonstrated by the fact that the 100th press-formed body is the same shape and size as the first pressed body, and that there are no cracks, flaws, or chips as with the upper punch, lower punch and die. The

M Granulated powder P which is a raw material powder P powder press compact 10 A device for manufacturing a powder press compact (powder press compacting device)
DESCRIPTION OF SYMBOLS 11 die plate 12 die 13 lower punch 14 die cavity 15 upper punch 16 hopper 17 feeder 18 flexible hose 19 drive rod 21 grand plate 22 base 23 column 24 column plate 26 lower ram

  The method for producing a powder-pressed compact according to the present invention can be used to easily and inexpensively produce a compact for a trial product such as a toy, a sundry product, an automobile part, and an electric part.

Claims (5)

In a method of manufacturing a powder pressed compact by pressing raw material powder filled in a die cavity formed by a lower punch and a die between the lower punch and the upper punch,
The mold comprising the lower punch, the upper punch and the die is a resin mold comprising a photocurable resin which does not contain a material other than a resin three-dimensionally shaped using an optical shaping method or a three-dimensional printer ,
The raw material powder is a spherical granulated powder having a particle size (D50) of 50 to 200 μm obtained by mixing a metal powder or ceramic powder and a binder, and the binder is contained in 100% by mass of the granulated powder. 12 to 12% by mass,
A method for producing a powdery press-formed product, characterized in that the press-molding of the granulated powder is performed at a press pressure of 50 to 300 MPa and a press temperature not higher than the heat resistance temperature of the resin mold.   The method according to claim 1, wherein the metal powder is iron powder, Ni powder, Co powder or a mixed powder thereof, alloy steel powder, stainless steel powder, corrosion resistant alloy powder, or magnetic alloy powder. Wherein the ceramic powder is zirconia (ZrO ₂₎ powder, alumina _(Al 2 _{O 3)} powder or method of producing a powder press molding body according to claim 1, wherein the aluminum nitride (AlN) powder.   The powder press molding according to any one of claims 1 to 3, wherein the binder is any one of polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), polyethylene glycol (PEG) or a combination thereof. How to make the body.   A method of sintering a powder press compact produced by the method according to any one of claims 1 to 4 to produce a sintered product.

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