JPH0578703A - Device for compacting metal powder - Google Patents

Abstract

PURPOSE:To conduct hot press bonding and forging in one stage at the time of compressing a powder filled in a punch hole with the upper and lower punches by demarcating a vacant space around an intermediate compact. CONSTITUTION:The step 2A of a lower punch 2 is inserted to the upper part 1A of a punch hole, and then an alloy powder P is filled in the upper part 1A. An upper punch 3 is lowered to hot-press-bond and compress the powder P. When the formed intermediate compact acquires an enough strength for forging, the lowering of the lower punch 2 is started, and the upper punch 3 is continuously lowered. When the intermediate compact is moved into the lower part 1B of the punch hole, the lower punch 2 is stopped, and the intermediate compact is further compressed by the descending upper punch 3. A cylindrical vacant space is formed at this time. The intermediate compact is crushed and expanded to the inner diameter of the lower part 1B, and a bulge is formed on the upper and lower ends. The material flows in the intermediate compact, hence the oxide film of each grain is broken, inter-granular cohesion is caused, and the compact is densified to a desired density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for molding aluminum alloy powder or Fe-based alloy powder,
In particular, it relates to an apparatus capable of continuously performing a hot pressing process and a forging process in one step.

[0002]

2. Description of the Related Art For example, a molded body made of an aluminum alloy containing Fe, V, Zr, Cu, Mg, Si and the like has excellent strength, rigidity, toughness, heat resistance and corrosion resistance. Since the surface of the aluminum alloy powder to be used is covered with a strong oxide film, it is difficult to break the oxide film of individual powder particles to form inter-particle bonds by the normal sintering molding method, and it is difficult to manufacture. Is.

Therefore, as a method for manufacturing this kind of aluminum alloy member, Japanese Patent Publication No. 1-20215 proposes the following manufacturing method.

In this method, first, an aluminum alloy powder is compressed in a molding die to have a density ratio of 65 to true density.
An 85% powder compact is molded (compacting step).

Next, after the powder compact is heated or sintered at a temperature of 300 ° C. or higher and a liquid phase formation temperature or lower (heating and holding step), it is extruded to a temperature of a density ratio of 95% or higher at a temperature within the above range. Or forged (main forming process),
Obtain a molded product.

According to this method, the powder compacting step and the heating and holding step are effective to secure the strength enough to withstand the subsequent main forming and to cause the material flow (deformation) in the main forming step. The oxide film can be destroyed to cause interparticle bonding to sufficiently densify and improve the characteristics of the molded body.

[0007]

However, in the above-mentioned manufacturing method, since the molded product is obtained through a total of three steps of the powder compacting step, the heating and holding step, and the main forming step, the workability in the main forming step is sufficient. However, cracking is likely to occur due to insufficient formability in the next step. In addition, it is difficult to increase the productivity because it takes time, and at least two types of processing devices are required, so that there is a drawback that the equipment becomes large.

In order to improve productivity, a method of coining or hot pressing a material powder to obtain a molded product at once can be considered. However, in order to break the oxide film of aluminum alloy particles by coining or hot pressing. However, it requires a considerably high pressure and / or a long pressurizing and holding time, which is not realistic.

The same problem as described above applies to Fe-based alloy powders. For example, C, Cu, Ni, Cr, M
In the case of forming a powder compact of a Fe-based alloy containing o, etc., hot pressing or green molding + sintering forging has been generally adopted. In order to obtain a strong bond of Fe-based alloy particles by binding forging, a considerably high pressure, a high heating temperature, and / or a long holding time are required. In addition to being costly, there was the problem of low productivity.

[0010]

The present invention has been made to solve the above problems, and includes a die having punch holes,
A metal powder molding apparatus comprising an upper punch and a lower punch which are inserted into the punch hole from above and below, and a driving means for vertically moving each of the punches. In the die, a die for heating the inside of the punch hole is provided. A heating means is provided and a space defining means is provided for defining an extra space around the intermediate compact when the powder filled in the punch holes is compressed by the upper punch and the lower punch. It has a feature.

The space defining means may be an expanded diameter portion formed on the upper or lower portion of the punch hole and having a relatively large inner diameter.

The space defining means is provided with one or more slide members which can form a part of the inner wall surface of the punch hole and which can move back and forth, and a driving means for moving the slide members forward and backward. Good.

Further, the driving means of the slide member may be a biasing means for biasing each slide member toward the inside of the punch hole.

Further, as a space defining means, the die is arranged so that a gap can be formed on the inner wall surface of the punch hole.
A die opening / closing mechanism that can be divided into the above die constituent members and that drives opening and closing of these die constituent members may be provided.

[0015]

In the metal powder molding apparatus of the present invention, the punched holes of the die are filled with the material powder, and the material powder is heated by the heating means, or after the heated powder is filled, the material powder is heated. It is compressed by a punch and a lower punch, and hot pressed to form an intermediate compact having a strength capable of withstanding forging. Subsequently, the space defining means is operated to define (or while defining) an extra space around the intermediate compact, and the intermediate compact is further compressed by the upper punch and the lower punch for forging.

As a result, the portion of the intermediate compact which faces the surplus space is opened, and the degree of freedom of deformation of the internal powder becomes greater than in the case of coining type compression molding. Therefore, the pressure required for the densification is small, and the oxide film of the powder particles is easily broken by the deformation, so that the bulk metal surface is exposed and the particles are bonded to each other. Therefore, it is possible to easily form a metal powder having a high degree of bonding due to an oxide film and easily cracking during compression to a high density ratio with a relatively low pressing force, and to improve ductility after reaching 100% density. Since the hot pressing and the forging process can be performed substantially in one step including the plastic deformation step of giving strain for improving the toughness, the productivity is enhanced.

[0017]

EXAMPLES Examples of the metal powder molding apparatus according to the present invention will be described below. FIG. 1 is a sectional view of the first embodiment,
Reference numeral 1 is a die having a cylindrical punch hole (1A + 1B), 2 is a lower punch inserted into the punch hole from below, and 3 is an upper punch inserted into the punch hole from above. The upper portion 1A of the punch hole is smaller in diameter than the lower portion 1B by a radius difference D, and there is a step portion 1C between them.

A heater (not shown) is provided inside the die 1 so that the temperatures of the die 1, the lower punch 2 and the upper punch 3 can be freely adjusted.

The outer diameter of the lower punch 2 is set to be slightly smaller than that of the lower punch hole 1B so that material leakage does not occur, and the outer diameter of the upper punch 2 is slightly smaller than the inner diameter of the upper punch hole 1A. A step portion 2A is formed. The outer diameter of the upper punch 3 is set to be slightly smaller than that of the upper punch hole 1A. The lower punch 2 and the upper punch 3 are separately driven up and down relative to the die by a driving mechanism (not shown).

In the case of this example, the cylindrical space formed around the upper punch 3 when the upper punch 3 descends to the position of the lower portion 1B is a surplus space. The radius difference D is preferably set so that the open ratio of the compressed material is 3 to 30%, more preferably 5 to 20%. The open ratio here is defined as the reciprocal of the extrusion ratio when the material flow toward the surplus space is considered as extrusion for convenience,
In this example, open ratio = (cross-sectional area of lower portion 1B−cross-sectional area of upper portion 1A) / cross-sectional area of lower portion 1B.

If the open ratio D is less than 3%, the effect of producing a sufficient material flow at the stage of forging the intermediate product is poor, and sufficient densification is difficult. When it is more than 30%, tensile stress is generated in the surface layer portion of the intermediate compact when the material flow occurs, and cracks are likely to occur.

As for the material of the die 1, the lower punch 2 and the upper punch 3, for example, when the material to be molded is an aluminum alloy, the material is tool steel, but the aluminum alloy easily adheres to the surface. Requires treatment or lubrication,
A C-based lubricant is effective as the lubricant. Further, in the case of Fe-based alloy, a material such as Ni alloy is suitable.

In order to use the apparatus for molding metal powder having the above-described structure, first, the alloy powder as a material is preheated to a liquidus temperature or lower by a preheating device (not shown), and then the lower punch 2 as shown in FIG. A predetermined amount of alloy powder P is put into the punch hole upper portion 1A in a state where the stepped portion 2A of the punch hole upper portion 1A is inserted into the punch hole upper portion 1A. Die 1, upper punch 3, lower punch 2 are also 150 ° C
~ Heat to about the same temperature as the powder.

Then, the lower punch 2 is not moved, and the upper punch 3 is lowered to compress the material powder P while hot pressing.
Let it be an intermediate compact Q. When the intermediate compact Q has a strength that can withstand forging, the lower punch 2 starts to descend. During this time, the upper punch 3 is continuously lowered without stopping. The descending speed of the lower punch 2 is set to be substantially equal to or higher than that of the upper punch 3, and both descend while fixing the intermediate compact Q therebetween. Intermediate compact Q is punch hole lower part 1
After moving into B, the lower punch 2 is stopped, and the lower punch 2 continues to descend, so that the intermediate compact Q in the lower punch hole lower portion 1B.
Is further compressed.

At this point, a cylindrical extra space is formed around the intermediate compact Q. This allows
As shown in FIG. 2, the intermediate compact Q is crushed and the punch hole lower part 1
Expanded to the inner diameter of B, and further bulged portion S in an annular shape at the upper and lower ends
Occurs. For this reason, a material flow occurs inside the intermediate compact Q, the oxide film of individual particles is broken, inter-particle bonds are formed, and it becomes possible to densify to a desired density ratio and further mold.

When the forged compact R is sufficiently densified, the lower punch 2 is lowered to pull it out from the die 1, and the upper punch 3 is further lowered to extrude the forged compact R from the die 1 and transfer it to the next step.

Next, as shown in FIG. 4, the lower punch 2 is returned to the initial position, the upper punch 3 is retracted upward, and the upper punch hole 1A is filled with powder. Hereinafter, similarly, the above cycle is repeated to obtain the molded bodies R one after another.

According to the apparatus for molding metal powder having the above-described structure, after forming an extra space around the intermediate compact Q, the intermediate punch Q is further compressed (forged) by the upper punch 3 and the lower punch 2. As a result, a material flow is generated inside the intermediate compact, so that the oxide film of the powder particles is easily broken along with the material flow, and the bulk metal surface is exposed and particles are bonded to each other.

Therefore, it is difficult to increase the degree of bonding due to the oxide film and to easily produce powder of aluminum alloy or Fe-based alloy, which easily cracks during compression, at lower pressure and temperature than hot pressing and sintering forging, and in a short time. In addition to the high density, it is possible to carry out the hot pressing and forging processes substantially in one step, so that the productivity is improved and the equipment is improved in comparison with the method of performing different kinds of molding in multiple stages. The cost is cheap.

In the above example, the punched hole has a circular cross-sectional shape for simplification, but it goes without saying that the shape of each part may be appropriately changed according to the article to be manufactured.

Next, FIGS. 5 to 8 are views showing a second embodiment of the present invention. In the figure, reference numeral 10 is a die, 10A is a punch hole, 12 is a lower punch, and 16 is an upper punch. The features of this example are that the outer circumferences of the lower punch 12 and the upper punch 16 are:
Cylindrical sleeves (slide members) 14 and 18 are passed through the sleeves 14 and 18, and the punches 1 and
6 is to be lifted and lowered independently. Sleeve 14,
The wall thickness of 18 is the same as the radius difference D in the first embodiment.

In order to manufacture an alloy member by using this apparatus, as shown in FIG. 5, after preheating the material powder P as in the above embodiment, the lower punch 12 and the lower sleeve 14 are aligned. 10 punch holes 10A are filled.

Next, as shown in FIG. 6, the upper punch 16 and the upper sleeve 18 are aligned and lowered, and at the same time, the lower punch 12 and the lower sleeve 14 are aligned and raised, and the material powder P is compressed to be the same as in the above-described embodiment. A similar intermediate compact Q is hot press-molded.

Further continuously, as shown in FIG. 7, the upper punch 16 is lowered and the upper sleeve 18 is raised relatively, while the lower sleeve 14 is lowered relative to the lower punch 12 and the intermediate is reached. The compact Q is compressed (forged).
As a result, a material flow occurs toward the annular extra space created by the retreat of the upper and lower sleeves 14 and 18, and the oxide film of the particles in the intermediate compact Q is broken and densified.

After that, as shown in FIG.
Then, the upper sleeve 18 is retracted upward, the lower punch 12 and the lower sleeve 14 are aligned and raised, and the compact R is ejected from the die 1 to complete one cycle.

According to the method of this embodiment, the following effects can be obtained in addition to the effects of the first embodiment. That is, in this example, the progress of the material flow and the formation of the surplus space can be accurately controlled by controlling the upper sleeve 18 and the lower sleeve 14 to move up and down, so that each sleeve 1 is attached to the tip (S) of the material flow.
These sleeves 14 and 18 can be retracted while constantly applying pressure by means of them. Then, as compared with the case where no pressure is applied to the tip of the material flow as in the first embodiment, tensile stress is less likely to occur at the tip end surface of the material flow, and cracks due to tensile stress are less likely to occur.

Further, since the shape of the front end portion (S) of the material flow can be controlled, by bringing the shape of the forged compact R close to the final shape of the product, there is also an advantage that the amount of processing after forming can be small. ..

The drive means for the sleeves 14 and 18 may be a structure in which the sleeves 14 and 18 are connected to the corresponding punches 12 and 16 via biasing means such as springs. The urging force of these urging means is set so that the sleeves 14 and 18 start to retreat due to the forming pressure when the hot pressing of the intermediate formed body Q is completed and the density ratio at which the intermediate formed body Q should be transferred to forging is reached. Is set. The use of such an urging means has an advantage that the structure of the apparatus can be simplified and that there are few failures and high operational reliability.

Next, FIGS. 9 to 13 show a third embodiment of the present invention, in which reference numeral 20 is a die, 22 is a lower punch, and 2 is a lower punch.
Reference numeral 4 denotes an upper punch, and in this example, a pair of slits 25, which open to the inner wall surface of the punch hole 20A so as to face each other, are formed inside the die 20, and a slide capable of sliding in the horizontal direction is formed in these slits 25. Each member 26 is inserted.

When the slide members 26 are fully inserted, the front end surfaces of the slide members 26 coincide with the inner wall surfaces of the punch holes 20A. The thickness of the slide member 26 is preferably about 5 to 30% of the height of 100% densification. The reason is the same as in the first embodiment.

An apparatus for molding metal powder using this apparatus is
Do as follows. First, as shown in FIG. 9, the preheated material powder P is filled in a state where the front end surface of each slide member 26 is aligned with the inner wall surface of the punch hole 20A. Next, as shown in FIG. 10, the upper punch 24 and the lower punch 22 are
After the powder P is hot-pressed to form an intermediate compact Q, the slide members 26 are retracted as shown in FIG.
At the same time, continue compression. As each slide member 26 retracts, a surplus space is generated and the material flows into the space, a convex portion S is formed, and the intermediate compact Q is densified to become a forged compact R.

Next, as shown in FIG. 12, the lower punch 22 is retracted, the upper punch 24 is lowered, the convex portion S is cut, and only the molded body R is ejected from the die 20. Furthermore, FIG.
As shown in FIG. 3, the upper punch 24 is retracted upward, the slide members 26 are returned, and the cut convex portions S are cut into the die 20.
To complete one cycle.

Also in this example, as in the second embodiment, since the material can be forged while being pressed by the slide members 26, tensile stress is unlikely to occur at the tip end S of the material flow, and cracks are generated. It has the advantage of being difficult to do. Further, since the convex portion S is cut along with the protrusion of the molded body R, when the convex portion S needs to be cut due to the inclusion of a lubricant or the like, the time and effort for post-processing can be saved accordingly.

Next, FIGS. 14 to 17 show a fourth embodiment of the present invention.
An example is shown, and in this example, the die is divided into an upper die 30 and a lower die 32, and the upper die 30 can be lifted by a driving mechanism. Reference numeral 36 is a lower punch, and 38 is an upper punch.

In this method, first, as shown in FIG. 14, the material powder P is filled in the punch holes 34 while the upper die 30 and the lower die 32 are in contact with each other. Next, as shown in FIG. 15, the powder P is hot-pressed by the upper punch 38 and the lower punch 36 to form an intermediate compact Q, and then the upper die 30 is raised by a certain length as shown in FIG. continue. As a result, an extra space 40 is generated between the upper die 30 and the lower die 32, the material flows into the extra space 40, and the convex portion S is formed.
The intermediate compact Q is densified and becomes a forged compact R.

Next, as shown in FIG. 17, after retracting the upper punch 38 upward, the lower punch 36 is raised, the convex portion S is cut, and only the compact R is ejected from the die for one cycle. Complete.

On the other hand, FIGS. 18 and 19 are improvements of the apparatus of the first embodiment. In the example of FIG. 18, a first step portion 50 and a second step portion 52 that expand in diameter in two steps are formed in the lower portion of the punch hole 1A. First, the material powder is hot-pressed in the upper portion of the punch hole 1A. After that, preliminary forging is performed in the first step portion 50, and main forging is further performed in the second step portion 52.

The open rate from the punch hole 1A to the first step portion 50 is 5 to 10%, and the open rate to the second step portion 52 is 10 to 30%.
It is desirable that it is a degree.

Also in this case, the upper punch continues to descend continuously, and the lower punch 2 descends stepwise in accordance with the punch pressure, so that hot press-bonding → pre-forging → main forging is continuously and seamlessly performed. It is possible to do.

On the other hand, FIG. 19 shows the lower portion 52 of the punch hole 1A.
Is formed in a tapered shape that opens downward. After hot pressing the material powder in the upper portion of the punch hole 1A, the lower punch 2 is gradually lowered while the intermediate punch is formed by the upper punch. Continue to forge and complete forging at the lowest position.

According to this, by adjusting the descending speed of the lower punch 2, it is possible to carry out forging while constantly applying pressure to the outer peripheral surface of the intermediate compact, so that the same effect as described above can be obtained. Compared to the example, the structure of the device is simple, but it has an advantage that cracks are less likely to occur on the outer peripheral surface of the intermediate molded body.

The sectional angle α of the tapered portion 54 is 3 to.
The angle is more than 15 °, preferably about 5-10 °. If it is less than 3 °, the effect of the present invention cannot be obtained, and if it exceeds 15 °, cracks are likely to occur in the molded body. Further, the taper portion 54 and the step portions 50, 52 and the like as described above may be combined.

20 and 21 are plan views showing still another embodiment. In this example, the die 60 is composed of four blocks (die constituting members) 62 which define a punch hole 60A in the center. It is configured.

Each block 62 is biased with a constant force toward the punch hole 60A, and when the pressure is further increased after forming the intermediate compact in the punch hole 60A, each block 62 is pressed.
Are separated from each other and the inner diameter of the punch hole 60A is expanded, and a gap 64 is formed between the blocks 62, and the intermediate compact is forged while causing a material flow in the radial expansion direction and in each of the gaps 64. ..

The present invention is not limited to the above embodiments, and the configurations of the embodiments may be combined.
The shapes of the die, the upper and lower punches, etc. may be arbitrarily changed, and any mechanism may be used as a mechanism for driving each part.

[0056]

[Experimental Example] Next, the effect of the present invention will be demonstrated with reference to an experimental example. As the material powder, aluminum alloy (AH09N,
Using AH12), rectangular parallelepiped aluminum alloy members were prepared by the methods of the following comparative examples and experimental examples, and their physical properties were compared. The composition of each of the above alloys is as follows. AH09N: Al-10Fe-1.5V-1.0Zr AH12: Al-8Fe-1.5V-1.0Zr

(Comparative Example) A rectangular parallelepiped aluminum alloy member was molded by the apparatus shown in FIG. Reference numeral 70 is a die, and the die 70 has a plan view of 12 mm × 57 mm.
The punch holes are formed and a heater is built in. 72 is a lower punch and 74 is an upper punch.

Each powder of AH09N and AH12 was previously added to about 4
After heating the die 70 to 150 ° C. while heating to 50 ° C., 30 g of powder is filled in the punch holes, and each punch 7
2,74 was compressed at a pressure of 10.6 ton / cm ² to obtain a molded body. The size of the compact is 12 x 57 x 14 m
It was m.

(Experimental Example 1) On the other hand, a rectangular parallelepiped aluminum alloy member was molded by the apparatus shown in FIG. Reference numeral 80 is a die, and reference numeral 82 is a lower punch, which are common to the die 70 and the lower punch 72, and have the same punch hole size.

Reference numeral 84 is an upper punch having a rectangular cross section, and slides 86 are arranged on both sides of the upper punch so as to be driven separately. The cross-sectional size of the upper punch 84 is 1
2 × 51 mm, cross-sectional dimension of slide 86 is 12 × 3 mm
Is.

45 powders of each of AH09N and AH12 were previously prepared.
After heating to 0 ° C. and the die 80 to 150 ° C., 30 g of powder is filled in the punch holes, the upper punch 84 and the slide 86 are aligned to compress the powder to a density ratio of 80%,
Further, each slide 86 was relatively retracted, the upper punch 84 was lowered, and finally compressed at a pressure of 10.6 ton / cm ² to obtain a molded body. The size of the compact is 12 x 57
X13.8mm, 12x3x16mm on both ends
Protrusions were formed.

Next, the above-mentioned four kinds of molded bodies are vertically divided into two,
The hardness at each point (25 points in total) of the cross section was measured by Rockwell B. Graphs showing the results in contour lines are shown in FIGS.

24 and 25 show the results of AH12, FIG. 24 is obtained by the method of the comparative example, and FIG. 25 is obtained by the method of the experimental example.

26 and 27 show the results of AH09N, FIG. 26 is obtained by the method of the comparative example, and FIG. 27 is obtained by the method of the experimental example. The hardness distribution corresponds to the density distribution. When I actually measured the density, Met. Further, FIGS. 28 and 29 are respectively shown in FIG.
And 25, and the results of FIGS. 26 and 27 are shown as a relationship between the pressing force and the density including other data.

As is clear from the above, according to the method of the experimental example, a material flow occurs inside the molded body, and the density is much higher, although the pressing force is the same as that of the method of the comparative example.

(Experimental Example 2) An experiment similar to Experimental Example 1 was conducted at a mold temperature of 450 ° C., and finally 4 ton / cm.
^At a pressure of ² , a molded product having a hardness and a density ratio equal to or higher than those of Experimental Example 1 was obtained.

[0067]

As described above, in the metal powder molding apparatus according to the present invention, the punching holes of the die are filled with the material powder, and the material powder is heated by the heating means, and then the material powder is punched. Then, the intermediate punch is compressed by the lower punch and hot pressed to form an intermediate compact having a strength enough to withstand forging. Subsequently, the space defining means is operated to define (or while defining) an extra space around the intermediate compact, and the intermediate compact is further compressed by the upper punch and the lower punch for forging.

As a result, the intermediate compact is allowed to deform as it compresses so as to fill the excess space, and the degree of freedom of deformation is imparted to the powder inside, so that the powder is densified and the oxide film of the powder particles is easily formed. The bulk metal surface is exposed and the particles are bonded to each other. Therefore, it is possible to easily form a metal powder having a high degree of bonding due to an oxide film and easily cracking during compression to a high density ratio with a relatively low pressing force, and to perform the hot pressing and forging processes substantially. Since it can be performed in one step, productivity is improved.

Further, in the case where one or more slide members capable of advancing and retreating forming a part of the inner wall surface of the punch hole and a driving means for advancing and retracting these slide members are provided as the space defining means. Since the material can be forged while the material is being pressed by the slide member, tensile stress is unlikely to occur at the tip of the material flow, and cracks are less likely to occur.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a hot press bonding process in a first embodiment of a metal powder molding apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a forging process in the first embodiment.

FIG. 3 is a vertical cross-sectional view showing a process of ejecting a molded body in the first embodiment.

FIG. 4 is a vertical sectional view showing a powder filling process in the first embodiment.

FIG. 5 is a vertical sectional view showing a powder filling process according to a second embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view showing a hot press-bonding process in the second embodiment.

FIG. 7 is a vertical cross-sectional view showing a forging process in the second embodiment.

FIG. 8 is a vertical cross-sectional view showing a process of ejecting a molded body in the second embodiment.

FIG. 9 is a vertical cross-sectional view showing the powder filling process in the third embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view showing a hot press-bonding process in the third embodiment.

FIG. 11 is a vertical cross-sectional view showing a forging process in the third embodiment.

FIG. 12 is a vertical cross-sectional view showing a process of ejecting a molded body in the third embodiment.

FIG. 13 is a vertical sectional view showing a post-treatment process in the third embodiment.

FIG. 14 is a vertical sectional view showing a powder filling process according to a fourth embodiment of the present invention.

FIG. 15 is a vertical cross-sectional view showing the hot press bonding process in the fourth embodiment.

FIG. 16 is a vertical cross-sectional view showing a forging process in the fourth example.

FIG. 17 is a vertical cross-sectional view showing a process of ejecting a molded body in the fourth example.

FIG. 18 is a vertical sectional view of an apparatus used in a fifth embodiment of the present invention.

FIG. 19 is a vertical sectional view of an apparatus used in a sixth embodiment of the present invention.

FIG. 20 is a plan view of the device used in the seventh embodiment of the present invention.

FIG. 21 is a plan view showing a forging process in the seventh example.

FIG. 22 is a vertical sectional view showing an experimental method of a comparative example.

FIG. 23 is a vertical sectional view showing an experimental method of an experimental example.

FIG. 24 is a graph showing the H _R B hardness distribution of the test piece obtained in the comparative example.

FIG. 25 is a graph showing the H _R B hardness distribution of the test piece obtained in the experimental example.

FIG. 26 is a graph showing the H _R B hardness distribution of the test piece obtained in the comparative example.

FIG. 27 is a graph showing the H _R B hardness distribution of the test piece obtained in the experimental example.

FIG. 28 is a graph showing a relationship between a pressing force and a molding density in an experimental example.

FIG. 29 is a graph showing a relationship between a pressing force and a molding density in an experimental example.

[Explanation of symbols]

 1 die 1A punch hole 2 lower punch 3 upper punch P material powder Q intermediate compact (hot pressure compact) R forging compact S material tip (convex) 10 die 10A punch hole 12 lower punch 14 lower sleeve ( Slide member 16 Upper punch 18 Upper sleeve (slide member) 20 Die 20A Punch hole 22 Lower punch 24 Upper punch 26 Slide member 30 Upper die (die component member) 32 Lower die (die component member) 34 Punch hole 36 Lower punch 38 Upper punch 40 Gap 50 First step (expanded part) 52 Second step (expanded part) 54 Tapered part (expanded part) 60 Die 60A Punch hole 62 Block (die component) 64 Gap

Claims (5)

[Claims] 1. A molding apparatus for metal powder, comprising: a die having punch holes; an upper punch and a lower punch which are inserted into the punch holes from above and below; and a driving means which drives the punches up and down. The die is provided with heating means for heating the inside of the punch hole, and when the powder filled in the punch hole is compressed by the upper punch and the lower punch, an excess space is formed around the compressed intermediate compact. An apparatus for molding metal powder, characterized in that a space defining means for defining the space is provided. 2. The apparatus for molding metal powder according to claim 1, wherein the space defining means is an expanded diameter portion having a relatively large inner diameter formed in an upper portion or a lower portion of the punch hole. .. 3. The space defining means includes one or two or more slide members that form a part of an inner wall surface of the punch hole and can move back and forth, and a driving means for moving the slide members forward and backward. The apparatus for molding metal powder according to claim 1, characterized in that. 4. The apparatus for molding metal powder according to claim 3, wherein the driving means is a biasing means for biasing each slide member toward the inside of the punch hole. 5. The die as the space defining means,
It is divisible into two or more die constituent members so that a gap can be formed on the inner wall surface of the punch hole, and a die opening / closing mechanism for driving the die constituent members to open and close is provided. Item 1. A metal powder molding apparatus according to Item 1.