JPH0740095A - Molding device for powder molded goods and molding method therefor - Google Patents

Abstract

PURPOSE:To uniformalize the density of the material powder to be packed in the upper part and lower part of a horizontal rod even if a cross hole is formed in powder molded goods by using the horizontal rod movable into and out of a die space. CONSTITUTION:A powder supply part B having a powder supply hole 21a formed in the horizontal rod 21 is exposed into the die space 17 at the time of supplying the material powder 15 into the die space 17. Compression molding is executed in the state of exposing a powder molding part A in the die space by moving the horizontal rod 21, by which the cross hole 25a is obtd.

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 a powder molded product which is capable of molding a lateral space molding portion, for example, a lateral hole, which is formed from the side surface of a powder molded product to be compression molded toward the inside. It relates to a molding method.

[0002]

2. Description of the Related Art A powder molded product is obtained by filling powder as a material into a mold space formed by an upper mold and a lower mold, compression molding in this state, and then sintering. Conventionally, for example, the following method has been used to form a lateral hole in such a powder molded product.

One is a method of mechanically forming a lateral hole in a molded product obtained by compression molding and then sintering, using a drilling machine such as a drill or a drilling machine.

Another method is, as disclosed in Japanese Utility Model Publication No. 2-16879, a punch for punching a lateral hole which is mounted so as to be retractable in a manner of penetrating a die and horizontally traversing a die space. There is one in which a horizontal hole is formed by the punching punch described above with respect to an annular molded product which is provided and compression-molded in the vertical direction by upper and lower molds. The punched dust is discharged to the outside through a hollow core rod that penetrates the axis of the lower die of the molded product.

However, in the former method, the sintered molded product has extremely high hardness and has minute pores, resulting in intermittent cutting, resulting in poor workability and reduced work efficiency, and perforation. Since the tool is often worn and damaged, the burden of the tool cost is increased, and the machining is a separate process, so that there is a problem that the manufacturing cost is high because the work is not continuous.

On the other hand, in the latter method, since the compression-molded molded product before sintering is brittle, when a horizontal hole is formed by a punching punch, defects such as cracks and chips are likely to occur, and the formed lateral Since the compressed powder for the holes is discharged as a waste, the yield of the material powder is deteriorated by that amount, and since the waste is discharged to the hollow core rod, the molded product can only be applied to hollow annular parts. . In addition, since the punch for punching the lateral holes needs to be driven with a large pressure, there is a problem that the driving device such as a hydraulic cylinder becomes large.

Therefore, in order to solve the above-mentioned problems, the applicant of the present application has an inner diameter equal to the inner diameter of the lateral hole of the molded product in the mold space formed between the upper mold and the lower mold. A horizontal rod with an outer diameter is provided so that it can be projected and retracted horizontally from the lateral direction, and the material powder is introduced into the mold space from the upper opening formed by raising the upper mold with the horizontal rod exposed in the mold space. After compressing and molding the material powder between the upper and lower molds,
We have developed a technique to pull out the horizontal rod.

[0008]

By the way, in such a technique, a method of machining a lateral hole in a molded product after sintering, or a method of punching a lateral hole in a compression molded molded product before sintering with a punching punch. Although various problems that occur in the forming method are solved, the density of the powder in each part of the powder molded product after compression molding was measured. It was found that there was a significant difference between the lower part of the powder molded product and the lower part of the powder molded product, and it was found that a uniform density was not obtained in the entire powder molded product.

FIG. 7 is a perspective view of a rectangular powder molded product after compression molding having a lateral hole 1 used for density measurement. The powder molded product has an upper part 5 divided by a cutting line 3. The densities of predetermined portions with the lower portion 7 were measured. Figure 8
Shows the density on the vertical axis and the number of moldings on the horizontal axis, and the solid line is for the upper part 5 and the broken line is for the lower part. According to this, the density of the lower part 7 is 0.10 g / c at the maximum than the density of the upper part 5.
It can be seen that m ^{3 is} low. It is considered that this is because the horizontal rod for forming the horizontal holes impedes the downward flow when supplying the material powder into the mold space, and the lower powder amount is insufficient as compared with the upper powder amount. .

Therefore, according to the present invention, even when a space forming portion, for example, a lateral hole, is formed from the side surface of the powder molded product toward the inner side by using the molding member which can project and retract from the lateral direction in the mold space, The purpose of the present invention is to make the density of the powder supplied from the upper part uniform between the upper part and the lower part of the powder molded product with the space molding part as a boundary.

[0011]

In order to achieve the above object, the present invention is, firstly, a mold main body having an upper mold and a lower mold forming a mold space filled with material powder from above. And a molding member capable of protruding and retracting from the side into the mold space by penetrating at least one side of the mold body,
In this molding member, a powder molding portion having a shape equal to the shape of the space molding portion in the lateral direction formed from the side surface of the powder molding product toward the inside, and the projected area in the vertical direction in the mold space of this powder molding portion A powder supply unit having a small projected area is provided.

Secondly, with respect to a mold body having an upper mold and a lower mold which form a mold space filled with material powder from above, a lateral direction formed from the side surface of the powder molded product toward the inside. A molding member having a powder supply part having a projection area smaller than the vertical projection area of the powder molding part having the same shape as that of the space molding part in the mold space is exposed to the mold space. The mold body is inserted through at least one side of the mold body so as to be in a state of being filled, and after the material powder is filled into the mold space from above, the molding member is molded to expose the powder molding part in the mold space. In this method, the material powder is moved relative to the mold body, and in this state the material powder is compressed from above and below to be pressed, and after completion of the pressing, the molding member is pulled out.

Thirdly, in the first configuration or the second method, the lateral space forming portion formed from the side surface of the powder molded product toward the inside is formed as a lateral hole.

Fourthly, in the first configuration or the second method, a pair of molding members are provided so as to penetrate the mold main body from both left and right sides, and can be projected from and retracted into the mold space from both left and right sides, The space forming portion in the lateral direction, which is formed from the side surface of the powder molded product toward the inside, is a concave portion formed by extending in the circumferential direction.

Fifthly, in the third structure, the powder supply portion has a powder supply hole penetrating in the vertical direction.

Sixthly, in the fourth structure, the powder supply portion is provided with a powder supply hole penetrating in the vertical direction, and the powder supply hole has a shape that is aligned with the mold space while being exposed to the mold space. is there.

[0017]

According to the first to sixth molding apparatuses or molding methods, the molding member penetrating the mold body is inserted into the mold space so that the powder supply portion is exposed, and in this state By filling the material powder, the material powder to be filled is exposed to the mold space because the vertical projected area of the powder supply portion is smaller than the same area of the powder molding portion. Even if it is, the shortage of powder supply to the lower part is suppressed, and the density of the powder molded product becomes uniform in the upper part and the lower part.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus for molding a powder molded article according to an embodiment of the present invention. This embodiment is applied to the case of forming a lateral hole which is a lateral space forming portion formed inward from a side surface of a cylindrical powder molded product. The press die used in this device is moved up and down by a cylindrical die 9 fixed to a die plate (not shown) and a pressure drive device (not shown), such as a hydraulic cylinder, and is moved downward into the axial center hole 9a of the die 9. And a columnar upper punch 13 that is vertically moved by a pressure driving device (not shown), for example, a crank mechanism, and is inserted into the shaft center hole 9a of the die 9 from above. ing. Here, the lower die is composed of the die 9 and the lower punch 11,
The upper punch 13 constitutes an upper die, and the upper and lower dies constitute a die body.

A mold space 17 filled with the material powder 15 is formed in the mold body between the axial hole 9a of the die 9 and the upper end surface of the lower punch 11. A feeder 19 for guiding the material powder 15 into the mold space 17 is installed on the upper surface of the die 9. After the material powder 15 is supplied into the mold space 17, the feeder 19 moves in the left-right direction to remove excess material powder.

At substantially the center of the die 9 in the vertical direction,
A circular through hole 9b penetrating in the left-right direction is formed, and a horizontal rod 21 as a molding member capable of horizontally protruding and retracting from the right side in the drawing into the mold space 17 is inserted into this through hole 9b. The horizontal rod 21 is horizontally driven by a horizontal drive mechanism 23 including a hydraulic or pneumatic fluid cylinder, for example.

As shown in detail in FIG. 2, the horizontal rod 21 has an outer diameter equal to the inner diameter of the lateral hole formed in the powder molded product, and approximately half of the distal end side is formed. The powder molding portion A is a portion having the same length as the lateral dimension of the mold space 17 in almost half. A powder supply hole 21a penetrating in the vertical direction in FIGS. 2A and 1 is formed at a position adjacent to the powder molding section A, which is the powder supply section B. The lateral dimension of the powder supply hole 21a is equal to the lateral dimension of the powder molding portion A. As a result, the vertical projected area of the powder supply part B in the mold space 17 is smaller than the projected area of the powder molding part A by the amount of the powder supply hole 21a.

In the apparatus for molding a powder molded product having such a structure, a powder molded product having lateral holes is molded in the order of (a) to (c) of FIG.

First, the lower punch 11 is the shaft center hole 9 of the die 9.
The mold space 17 is formed by being fitted into the a from below and stopping at a predetermined position. The horizontal rod 21 inserted into the through hole 9b of the die 9 is moved by the horizontal drive mechanism 23 so that the powder supply part B is exposed to the mold space 17. In this state, the material powder 15 is filled in the mold space 17 via the feeder 19. At the time of filling, the material powder 15 passes through the powder supply hole 21a at the portion where the horizontal rod 21 is present, so that the horizontal rod 21 is sufficiently supplied below the horizontal rod 21 without interfering with it. The filling amount is shown in Figure 1.
As shown in (a), the amount is set to be sufficient so as to protrude from the mold space 17. At this time, by vibrating the horizontal rod 21, the powder supply hole 21 made of the material powder 15
The clogging of a is prevented. In addition, the horizontal rod 21
As shown in FIG. 3, a predetermined angle θ is set to rotate about the axis.
By adding the motion of rocking in the range of, the area where the powder can be supplied is expanded, which is more effective.

In the state shown in FIG. 1 (a), the feeder 19 is moved in the left-right direction and the excess material powder 15 supplied to the upper portion.
And the horizontal drive mechanism 23 is operated to move the horizontal rod 21 to the right in the drawing so as to pull it out from the die 9, so that the powder molding part A at the tip is exposed to the mold space 17. To do. This state is shown in FIG.
At this time, the material powder 15 that has entered the powder supply hole 21a of the powder supply section B is brought into the die 9 as the horizontal rod 21 moves. When the powder supply part B is exposed to the mold space 17 in the cycle, the powder is supplied into the mold space 17 and is not wasted.

Next, as shown in FIG. 1C, the upper punch 13
The lower punch 11 is also raised and fitted deeply into the mold space 17 at the same time as the lower punch 11 is lowered and fitted into the mold space 17.
As a result, the material powder 15 becomes the upper punch 13 and the lower punch 1.
1 and the material powder 1 is to be pressed from above and below.
5 is compression molded to a predetermined density, and a compression molded product 25 is obtained. At this time, since the powder molding portion A of the horizontal rod 21 exists in the mold space 17, the powder molding portion A forms the lateral hole 25a.

At the time of this pressurization, it is necessary to apply a uniform compression ratio in the vertical direction in order to prevent deformation due to an unbalanced load. For that purpose, the moving distance until the upper punch 13 completes the pressing on the upper surface of the material powder 15 and the moving distance until the lower punch 11 completes the pressing on the lower surface of the material powder 15. The lower punch 11 with respect to the descending speed of the upper punch 13 is proportional to the ratio.
Set the rising speed of. For example, the upper punch 13
When the moving distance of the lower punch 11 is equal to that of the lower punch 11, the descending speed of the upper punch 13 and the ascending speed of the lower punch 11 are set equal, and the moving distance of the upper punch 13 is 2 with respect to the moving distance of the lower punch 11. In case of double, upper punch 13
The descending speed of is set to twice the ascending speed of the lower punch 11.

After the compression molding, the punches 1 above and below each punch 1 are separated by a small distance, for example, within 5% of the height of the compression molded product 25.
Retract 3 and 11 equally, and pull out the horizontal rod 21 in this state. This reduces the force applied to the horizontal rod 21 when the horizontal rod 21 is pulled out, and prevents the horizontal drive device 23 from increasing in size and the life of the mold from being shortened.

After pulling out the horizontal rod 21, the compression molded product 25 is held by the upper and lower punches 13 and 11, respectively.
The upper and lower punches 13 and 11 are raised to a position where the upper end surface of the lower punch 11 coincides with the upper surface of the die 9, so that the compression molded product 25 is extracted from the mold space 17 to the outside.
The extracted compression-molded product 25 is discharged from the mold to the next step by the feeder 19. Then lower punch 11
Is lowered to form a mold space 17 with the die 9 as shown in FIG. 1A, and a horizontal rod 21 is inserted into the mold space 17 to prepare for the next molding cycle.

The compression molded product 25 thus obtained
Since the material powder 15 is sufficiently filled under the horizontal rod 21 as well, the density of the material powder does not become lower in the lower portion of the horizontal rod 21 than in the upper portion, and a uniform density distribution is obtained as a whole. can get. FIG. 4 shows the density (shown by a solid line) of the material powder 15 on the upper side of the horizontal hole 25a formed by the horizontal rod 21 and the same density (shown by a broken line) on the lower side, and FIG. It can be seen that there is no large difference in density compared to the conventional case shown in.
Moreover, since the material powder 15 can be uniformly supplied as a whole, the bending stress applied to the horizontal rod 21 during compression molding can be reduced, and the life of the horizontal rod 21 can be improved.

Although the size of the powder supply hole 21a greatly varies depending on the shape of the horizontal rod 21, the horizontal rod 2
When 1 is 8 mm in diameter, the vertical projection area of the powder supply part B exposed in the mold space 17 is free within the range that can secure 1% or more of the same projection area of the powder molding part A according to the experimental result. is there.

FIG. 5 shows the horizontal rod 2 in the above embodiment.
Instead of the first powder supply hole 21a, recesses 21b are provided on both sides, and this part is used as the powder supply section B. In this case, the material powder 15 when being supplied to the mold space 17 is
Since it passes through the concave portion 21b of the horizontal rod 21, the material powder 15 is sufficiently supplied even under the horizontal rod 21, and the same effect as that of FIG. 2 is obtained.

FIG. 6 shows another embodiment of the present invention. In this embodiment, a molding member for molding a space molding portion in the lateral direction from the side surface of the powder molded product to the inside can be penetrated from the left and right sides of the mold body to be horizontally projected and retracted in the mold space 17. Two flat plate-shaped cam dies 27 and 29 are used, and by using this, a powder molded product having an entire circumference undercut portion having an annular groove as a concave portion is obtained. Similar to the horizontal rod 21 in the above-mentioned embodiment, the cam dies 27 and 29 are individually horizontally driven by a horizontal drive mechanism (not shown) including a hydraulic or pneumatic fluid cylinder.

In the die 31 in this case, the lower die 33 and the upper die 35 can be separated from each other.
The circular axial holes 33a and 35a are formed in the. The lower punch 37 is inserted into the shaft center hole 33a of the lower die 33 from below.
The upper punch 39 is inserted into the shaft center hole 35a of the upper die 35 from above.
Are inserted respectively. Here, the die 31 and the lower punch 37 constitute a lower die, the upper punch 39 constitutes an upper die, and the upper and lower dies constitute a die body. A feeder 41 is provided on the upper surface of the upper die 35, and the upper and lower dies 35 and 33 have axial holes 33a and 35a and the lower punch 3 respectively.
A mold space 43 filled with the material powder 15 is formed in the mold body between the upper end surface of the mold 7.

The cam dies 27, 29 are movably arranged in the left-right direction between the lower die 33 and the upper die 35, and semicircular portions 27a, 29a are formed at the tips thereof, and the tips of the two are abutted. Then, the powder molding part A having a circular hole is formed. The circular hole of the powder molding portion A is smaller than the shaft center holes 33a and 35a. The cam die 29 adjacent to the powder molding portion A has a powder supply hole 29 having a diameter substantially the same as that of the shaft center holes 33a and 35a.
b is formed to form the powder supply unit B.

In the apparatus for molding a powder molded product having the above-described structure, a powder molded product having a full circumference undercut portion is molded in the order shown in FIGS. 6 (a) to 6 (d).

First, as shown in FIG.
Is fitted into the axial center hole 33a of the lower die 33 from below and stopped at a predetermined position, whereby the mold space 43 is formed.
The cam dies 27 and 29 are a lower die 33 and an upper die 35.
And the cam die 27 is pulled out between
9 is pushed in so that the powder supply hole 29b of the cam die 29 is aligned with the shaft center holes 33a and 35a. In this state, the material powder 15 is filled in the mold space 43 via the feeder 41. The filling amount is a sufficient amount so as to protrude from the mold space 43.

When the material powder 15 is filled in the mold space 43, the cam die 29 has the powder supply hole 29b and the shaft center hole 33.
The cam dies 29 are not exposed in the mold space 43 because they are aligned with a and 35a. Therefore, at this time, the material powder 15 does not interfere with the cam dies 29 and is sufficiently below the cam dies 29. Will be supplied.

From the state (a), the feeder 41 is moved in the left-right direction to remove the excess material powder 15 supplied to the upper portion, and the cam dies 27 and 29 are kept in a state where their tips are abutted to each other in the figure. Is moved to the right so that the center of the powder molding portion A and the centers of the shaft center holes 33a and 35a are at the same position. This state is (b). At this time, the material powder that has entered the circular hole of the powder supply section B moves with the movement of the cam dies 27, 29 and the lower die 33.
And the upper die 35, the material powder 15a brought into the die space 4 moves to the die space 43 in the next molding cycle.
Since it will be supplied to the inside of No. 3, it is not wasted.

Next, as shown in (c), the upper punch 39 is lowered to fit into the mold space 43, and at the same time, the lower punch 37 is raised to fit deeply into the mold space 43. As a result, the material powder 15 is pressed from above and below by the upper punch 39 and the lower punch 37, so that the material powder 15 is compression molded to a predetermined density, and the compression molded product 45 is obtained. At this time, the cam dies 27, 29 are placed in the mold space 43.
Since the powder molding part A exists, the powder molding part A forms an annular groove 45a. afterwards,
The compression molded product 45 is extracted from the mold space 43 to the outside by pulling out the cam dies 27 and 29 individually to the left and right and raising the upper punch 39, the upper die 35, and the lower punch 37.

Also in this embodiment, the compression molded product 45 is used.
Is a groove 45a formed by the cam dies 27 and 29.
Since the material powder 15 is sufficiently filled in the lower part of the groove, the density of the material powder does not decrease in the lower part of the groove 45a, and a uniform density distribution can be obtained as a whole.

[0042]

As described above, according to the present invention, the powder molding part is formed in the molding member having the powder molding part for molding the space molding part in the lateral direction from the side surface of the powder molded product toward the inside. A powder supply unit having a projected area smaller than the vertical projected area in the mold space is provided, and the material powder is filled from the upper part of the mold space with the powder supply unit exposed in the mold space. Therefore, the material powder to be filled is supplied through the powder supply unit having a small projected area in the vertical direction, the supply shortage below the molding member is suppressed, and the density of the powder molded product is reduced to the upper and lower parts. Can be made uniform.

[Brief description of drawings]

FIG. 1 is a working process diagram of a powder molding product molding apparatus showing an embodiment of the present invention.

FIG. 2 is a detailed view of a horizontal rod used in the molding apparatus of FIG.

FIG. 3 is an operation explanatory view showing a state in which the horizontal rod of FIG. 2 is caused to swing.

FIG. 4 is an explanatory diagram showing the densities of the material powder in the upper and lower portions of the lateral hole of the powder molded product by the molding device of FIG.

FIG. 5 is a detailed view showing another example of the horizontal rod of FIG.

FIG. 6 is a working process diagram of a molding apparatus for a powder molded product showing another embodiment of the present invention.

FIG. 7 is a perspective view of a rectangular powder molded product after compression molding having lateral holes.

FIG. 8 is an explanatory diagram showing the densities of the material powder in the upper and lower portions of the lateral hole of the powder molded article according to the conventional example.

[Explanation of symbols]

 9,31 Die (lower mold) 11,37 Lower punch (lower mold) 13,39 Upper punch (upper mold) 15 Material powder 17,43 Mold space 21 Horizontal rod (molding member) 21a Powder supply hole 25, 45 compression molded product (powder molded product) 25a horizontal hole (horizontal space molding part) 45a recess (horizontal space molding part) 27, 29 cam die (molding member) 29b powder supply hole A powder molding part B powder supply part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B30B 11/02 F 9347-4E

Claims (6)

[Claims] 1. A mold body having an upper mold and a lower mold for forming a mold space filled with material powder from above, and the mold space penetrating at least one side of the mold body. And a powder molding part having a shape equal to the shape of the lateral space molding part formed inward from the side surface of the powder molded product, and the powder. And a powder supply unit having a projected area smaller than the projected area of the molding unit in the mold space in the vertical direction, respectively. 2. A lateral space forming which is formed from a side surface of a powder molded article toward an inner side of a mold body having an upper mold and a lower mold which form a mold space filled with material powder from above. A molding member having a powder supply part having a projection area smaller than the vertical projection area of the powder molding part having the same shape as that of the powder molding part in the mold space, and the powder supplying part is exposed to the mold space. So as to penetrate through at least one side of the mold body, and after filling the mold space with the material powder from above, a molding member is provided to expose the powder molding part in the mold space. Move against
In this state, the material powder is compressed from above and below to be pressed, and after the pressurization is completed, the molding member is pulled out, and a method for molding a powder molded product. 3. A molding apparatus for a powder molded product or a molding method thereof according to claim 1, wherein the lateral space molding portion formed from the side surface of the powder molded product toward the inside is a lateral hole. . 4. The molding member is capable of penetrating from the left and right sides of the mold body and protruding from and retracting into the mold space from the lateral side, and a lateral space molding portion formed from the side surface of the powder molded product toward the inside. 3. The molding apparatus for a powder molded article or the molding method thereof according to claim 1 or 2, wherein is a recess formed by extending in the circumferential direction. 5. The molding apparatus for a powder molded article or the molding method thereof according to claim 3, wherein the powder supply section has a powder supply hole penetrating in the vertical direction. 6. The powder supply part is provided with a powder supply hole penetrating in the vertical direction, and the powder supply hole has a shape that is aligned with the mold space while being exposed to the mold space. 4. A molding apparatus for a powder molded article according to 4, or a molding method thereof.