JP3144450B2 - Mold for compacting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green compact forming die for forming a green compact by pressing a metal powder into a predetermined shape when manufacturing a sintered part.

[0002]

2. Description of the Related Art Sintered parts are manufactured by molding a metal powder into a predetermined shape using a powder molding die to form a green compact, and then sintering the green compact.

For example, in order to form a green compact (1) having a sectional shape as shown in FIG. 8, a powder molding die (2) as shown in FIGS. 10 to 13 is used. Powder molding die (2)
Consists of a lower mold (3) and an upper mold (4), and a lower mold (3)
Are cylindrical dies (5) and cylindrical first
The lower punch (6), the cylindrical second lower punch (7), and the axial third lower punch (8) are arranged concentrically, and the second lower punch (7) is fixed to the base plate (10). The die (5), the first lower punch (6), and the third lower punch (8) are supported so as to be able to move up and down relatively. The die (5) and the first to third lower punches (8) are moved up and down to form a cavity (12) for accommodating the metal powder (11).

The upper die (4) has a cylindrical first upper punch (14) and an axial second upper punch (15) arranged concentrically on a die set (13) from the outer peripheral side. (13) is held relatively up and down, and is relatively moved up and down by a cylinder (16) provided in the die set (13). A first piston (17) provided above the first upper punch (14) and a second piston (20) provided above the second upper punch (15) are arranged in the cylinder (16). , Die set (13)
From the first port (21) formed in the fluid passage (22)
The pressure fluid is simultaneously supplied to the upper and lower portions of the first piston (17) and the second piston (20) through (23),
A pressure fluid is supplied from the port (24) to the space between the first piston (17) and the second piston (20) through the fluid passage (24).

[0005] The green compact (1) is formed through a plurality of steps such as powder filling, powder movement, pressing, and release. In the powder filling step, as shown in FIG. 10, the die (5) of the lower die (3), the first lower punch (6), and the third lower punch (8) are raised to predetermined positions to form a cavity (12). And
The metal powder (11) is filled in the cavity (12). On the other hand, in the upper die (4), a pressurized fluid is supplied to the second port (24) to lower the first upper punch (14) and raise the second upper punch (15).

Next, in the powder transfer step, the die set (1
The ram (26) with the attached 3) is lowered, and the first lower punch (6) is moved by a rod (not shown) provided on the ram (26).
The support table (6a) supporting the table is depressed, and FIG.
As shown in FIG. 1, the first lower punch (6) is lowered to the height of the second lower punch (7) to deform the cavity (12) to move powder, and the first upper punch (14) is moved to the cavity. (12) to enter the metal powder (11) into a shape before final compression.

Next, in the compression step, as shown in FIG. 12, while the ram (26) descends to the bottom dead center, the second upper punch (1)
5) starts the compression first, and then the first upper punch (14) starts the compression to compress the metal powder (11) to form the green compact (1). That is, at the start of pressurization, the first upper punch (14) relatively rises and stops until the first piston (17) hits the intermediate wall (27) of the die set (13), and compression starts after the contact. Then, the third lower punch (8) descends to a predetermined position to compress the entire area of the metal powder (11) at a predetermined compression ratio.

In the release step, as shown in FIG. 13, after the die (5) is lowered, the ram (26) is raised. When the die (5) is raised, the pressurized fluid is supplied to the first port (21) of the die set (13). The first upper punch (14) is supplied to the die set (1).
3), the second upper punch (15) is relatively lowered, and the green compact (1) is pressed by the second upper punch (15). (14) is separated from the green compact (1), and after the first piston (17) contacts the second piston (20), the second upper punch (15) is also separated from the green compact (1). The green compact (1) is released from the mold.

When the ram (26) rises to the top dead center after release, a pressurized fluid is supplied to the first port (21) of the die set (13) to lower the first upper punch (14), In addition, the second upper punch (15) is raised.

When releasing the green compact (1), a die (5)
Moves away from the green compact (1) in advance, the green compact (1) is elastically restored (spring back) by the green compact (1).
Bites into the inner surface of the first upper punch (14),
The first upper punch (14) and the second upper punch (1
When 5) is raised, chipping tends to occur in the green compact (1).
Therefore, the first upper punch (14) and the second upper punch (1
5) so that both can be raised and lowered, and the first
By moving the upper punch (14) and the second upper punch (15) relatively, the protruding state of the lower end of the punch is reversed, and the green compact (1) is continuously pressed by the second upper punch (15). The first upper punch (14) is released in a state where the spring back of the green compact (1) in the horizontal direction is suppressed.

[0011]

As described above, when a so-called W punch mechanism is used for the upper die (4), the green compact (1) can be released without chipping. However, as shown in FIG.
In the case of molding a green compact (32) having a cross-sectional shape having 1), there are the following problems.

In order to form the green compact (32) having the above-described shape, three types of upper punches are required for the upper die. As shown in FIG.
A cylindrical first upper punch (14) on the die set (13),
The cylindrical second upper punch (15) and the axial third upper punch (33) are arranged concentrically, and the first upper punch (14) is fixed to the lower surface of the die set (13). (13) has a second upper punch (15) and a third upper punch (3
3) is mounted so that it can be moved up and down relatively, and the built-in cylinder (1
In 6), the second upper punch (15) and the third upper punch (33)
And the upper die (4) that is relatively raised and lowered.

However, in the molding by the upper die (4), the relative movement amount of the second upper punch (15) with respect to the first upper punch (14) and the third upper punch (33) is limited. If the heights of the projections (30) and (31) of the green compact (32) are different, the whole cannot be formed at a uniform compression ratio.

That is, in forming the green compact (32), the first upper punch (14) to the third upper punch (33) are used in the powder moving step.
However, the metal powder is formed into a shape having a height that allows for a predetermined compression ratio with respect to the green compact (32), and thereafter, compression is performed. The compression ratio at this time is determined by each convex portion (30
a) The height of (31b) is a · b, the height of each convex portion (30) (31) after compression is A · B, and the second upper punch (1
If the stroke of 5) is c, the compression ratio of one convex portion (30) is a / A, and the compression ratio of the other convex portion (31) is b / B. A is (ac), B is (b-
c). Accordingly, the compression ratios are respectively a / (ac) and b / (bc), and a and b must be the same in order for both to have the same value. That is, the lower surfaces of the first upper punch (14) and the second upper punch (15) must be at the same height. That is, unless the heights of the projections (30) and (31) of the green compact (32) are the same, molding with a constant compression ratio cannot be performed.

To solve this problem, a first upper punch (14), a second upper punch (15), and a third upper punch (3) are used.
3) may be held by the die set (13) so as to be able to move up and down relative to each other, and each may be operated independently by the cylinder. However, when a plurality of cylinders are provided in the die set (13), there is a problem that the structure becomes complicated and control of the operation of each cylinder becomes very troublesome.

An object of the present invention is to provide an upper mold for powder molding in which a plurality of upper punches can be operated at different strokes only by switching a set of cylinders.

[0017]

SUMMARY OF THE INVENTION The present invention is directed to a compact molding die for press-molding compacts having different thicknesses in at least three places in the pressing direction, and is integrally attached to a vertically movable die set. A fixed punch, a first movable punch adjacent to the fixed punch, and arranged to be able to move up and down in the die set with a stroke d; and a first movable punch adjacent to the first movable punch, and Lifting stroke d of movable punch
A second movable punch disposed so as to be able to ascend and descend to the die set with a shorter stroke e, and disposed between the die set and the first movable punch, wherein the first movable punch is moved to a raised position or Driving means for selectively driving to a lowered position;
An urging means for constantly urging the second movable punch toward the die set; and a biasing means disposed between the first movable punch and the second movable punch, wherein the first movable punch is provided with the die. A compacting die having an engaging means for engaging the first movable punch with the second movable punch when separated from the set by a stroke (de) or more.

The other mold includes a first movable punch disposed on a vertically movable die set so as to be movable up and down with a stroke d, and a first movable punch adjacent to the first movable punch and having the first movable punch. A second movable punch disposed so as to be able to ascend and descend to the die set with a stroke e shorter than the elevating stroke d, and a shorter than the elevating stroke e of the second movable punch adjacent to the second movable punch A third movable punch disposed to be able to move up and down on the die set with a stroke f; and a third movable punch disposed between the die set and the first movable punch, wherein the first movable punch is raised or lowered. A driving means for selectively driving the first movable punch and the third movable punch, and a biasing means for constantly biasing the second movable punch and the third movable punch toward the die set side; Arranged between An engagement means for engaging the first movable punch with the second movable punch when the first movable punch is separated from the die set by a stroke (de) or more; The second movable punch is disposed between the third movable punch and the second movable punch when the second movable punch is separated from the die set by a stroke (ef) or more. And engaging means for engaging.

[0019]

The mold having the above structure moves the first movable punch relatively up and down as the die set moves up and down.
The fixed punch, the first movable punch, and the second movable punch can be moved up and down with different strokes, respectively, and can be formed with an optimum stroke for different thickness portions of the green compact.

In addition, by moving the first movable punch relatively up and down with the ascending and descending operation of the die set, other molds are also provided.
The first movable punch, the second movable punch, and the third movable punch can be moved up and down with different strokes, respectively, and the compacts having different thicknesses can be formed with optimal strokes.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the embodiment of the present invention is applied to an upper die having a punch having a three-part structure will be described below with reference to FIGS.

As shown in FIG. 1, the upper die (35) is provided with a cylindrical fixed punch (37) and a cylindrical first movable punch (40) on a die set (36), and a shaft-shaped second movable punch (40). The movable punch (41) is arranged concentrically, the fixed punch (37) is fixed to the lower surface of the die set (36), and the first movable punch (40) and the second movable punch (41) are die set ( 36), it is held relatively up and down.

An annular first cylinder (42) is formed inside the die set (36) as a driving means, and a piston (4) provided on the upper part of the first movable punch (40).
3) is arranged inside the first cylinder (42) and on the outer periphery of the intermediate shaft portion (44) provided at the center of the die set (36). Further, a second cylinder (45) is formed as an urging means on the inner peripheral surface of the first movable punch (40), and a piston portion (46) provided on an outer peripheral surface of an intermediate portion of the second movable punch (41). Are arranged in the second cylinder (45). The upper surface of the piston portion (46) of the second movable punch (41) has a spacer (47) interposed to change the stroke. Also the second
A groove (50) is formed in the center of the upper end of the movable punch (41), and a guide formed in the center of the lower surface of the intermediate shaft (44) of the die set (36) in the groove (50). Shaft (5
1) is slidably fitted.

A first cylinder (4) is formed from a first port (52) formed in the die set (36) through a fluid passage (53).
Supply pressure fluid to the upper part of the piston (43) in 2),
A pressure fluid is supplied from a second port (54) formed in the die set (36) to a lower portion of the piston (43) in the first cylinder (42) through a fluid passage (55). Further, a pressure fluid is supplied from the third port (57) formed in the die set (36) to the lower part of the piston (46) in the second cylinder (45) via the fluid passages (60) and (61). It is.

A pressure fluid is supplied to the first port (52) or the second port (54) by selectively switching from a common fluid supply device (not shown) to provide a first movable punch (40). Is set up and down, and the third port (5
7) is supplied with a pressurized fluid at all times to provide the second movable punch (4).
The rising pressure is always applied to 1), and the second movable punch (4
The piston part (1) of (1) is set so as to be engaged with and pressed against engaging means, for example, a stopper (62) provided above the second cylinder (45). When the first movable punch (40) is at the lower end, a gap (stroke) (d) is opened between the upper end of the first movable punch (40) and the die set (36), and the second movable punch (40) is opened. The upper end of the punch (41) and the intermediate shaft (4) of the die set (36)
4) is set so as to open a gap (stroke) (e). In this case, the stroke (d) is set larger than the stroke (e). The stroke difference (d
-E) are convex portions (30) and (3) of the green compact (32) to be molded.
It is adjusted to the height difference of 1). The second cylinder (4
5) is formed sufficiently longer than the stroke difference (de).

On the other hand, the lower die (63) has a cylindrical die (6).
4) and the cylindrical first lower punch (65), the cylindrical second punch
A lower punch (66) and a third axial lower punch (67) are arranged concentrically so as to form a cavity (70) having a predetermined shape in the die (64) (see FIG. 2).

The molding operation of the mold will be described. The cavity (7) formed in the die (64) in the powder filling process
Fill metal powder into 0). As shown in FIG. 1, the upper die (35) waiting above has a first port (52) and a third port (52).
A pressure fluid is supplied to the port (57), the first movable punch (40) is lowered, and the second movable punch (41) is relatively raised, and the piston (46) is moved to the second cylinder ( 45) is pressed against the stopper (62).

Next, the ram (71) is lowered in the powder moving step, and the first lower punch (65) to the third lower punch (6) are moved by an adjusting rod (not shown) provided on the ram (71).
7) The support table (not shown) supporting the lower part is pushed down to lower the first lower punch (65) to the third lower punch (67) to deform the cavity (70), and as shown in FIG. The powder is moved, and the metal powder (11) is formed into a predetermined shape before compression.

Next, the ram (71) is lowered to the bottom dead center in the pressurizing step, but the pressure of the ram (71) is higher than the pressure of the first cylinder (42) supporting the first movable punch (40). Rises, the first movable punch (40) and the second movable punch (41) relatively rise, and firstly, the fixed punch (37) starts compression. Then, as shown in FIG. 3, the upper end of the second movable punch (41) is
When the second movable punch (41) hits the intermediate shaft portion (44) of (6), the second movable punch (41) is pushed down by the die set (36) and descends.
Start compression. The first movable punch (40) still continues to ascend relatively, and when the upper end of the first movable punch (40) hits the die set (36), it is pushed down by the die set (36) and then descends to compress. To start. Then, as shown in FIG. 4, all compression is completed at the bottom dead center of the ram (71).

Next, in the release step, the ram (71) rises after the dice (64) descends, and at the same time, the first port (52).
And the first movable punch (40) is relatively lowered. Then, as shown in FIG. 5, the fixed punch (37) and the second punch (37) are integrated with the ram (71) while the green compact (32) is first held down by the first movable punch (40).
The movable punch (41) is lifted and released from the mold, and the piston (46) of the second movable punch (41) is moved to the second cylinder (4).
When the stopper (62) of (5) is hit, the second movable punch (41) stops, and then the lower end of the piston (43) of the first movable punch (40) is moved to the lower step () of the die set (36). 72), the first movable punch (40)
Then, the second movable punch (41) rises, and the first movable punch (40) is also released.

As described above, in the pressing step, the first movable punch (40) and the second movable punch (41) can be moved independently with different strokes (d) and (e). Even if the heights of the projections (30) and (31) of the powder (32) are different, the entire area can be compressed at a uniform compression ratio.

As shown in FIG. 6, a die set (73)
The cylindrical fixed punch (74), the cylindrical first movable punch (75), and the cylindrical second movable punch (7)
6), the third axially movable punch (77) is arranged concentrically, and the fixed punch (74) is die set (73).
The first movable punch (75), the second movable punch (76), and the third movable punch (77) are held by the die set (73) so as to be able to move up and down. 75) can be moved up and down by a first cylinder (80) provided in a die set (73), and a second movable punch (7
6) can be moved up and down by a second cylinder (81) provided in the first movable punch (75), and the third movable punch (77) is provided in the second movable punch (76). The third cylinder (82) can be moved up and down, and a pressure fluid is constantly supplied to the second cylinder (81) and the third cylinder (82) to make the second movable punch (76) and the third movable punch (77). Is configured to always apply a rising pressure to the pressure. Then, the second movable punch (76) is connected to the first movable punch (7).
Stop at the intermediate stroke at 5), and move to the third movable punch (7
7) is stopped at an intermediate stroke by the second movable punch (76). Then, a green compact (86) having a plurality of convex portions (83), (84), and (85) as shown in FIG. 7 can also be formed with a uniform compression ratio. In this case, the stroke (d) of the first movable punch (75) and the second movable punch (7)
The stroke (e) of 6) and the stroke (f) of the third movable punch (77) are set so as to gradually decrease inward. Similarly, it is possible to form a green compact having more convex portions.

[0033]

According to the present invention, a fixed punch or a plurality of movable punches can be moved with different strokes, and a green compact having convex portions having different heights can be easily formed at a uniform compression ratio. it can. In addition, the mold only needs to have the driving means for operating the first movable punch and the urging means for constantly pressing the remaining second and third movable punches to the die set. Also becomes easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an upper mold according to the present invention.

FIG. 2 is a cross-sectional view at the time of a powder moving step during molding by the upper mold of the present invention.

FIG. 3 is a cross-sectional view at the time of a pressing step during molding by the upper mold of the present invention.

FIG. 4 is a cross-sectional view at the time of a pressing step during molding by the upper mold of the present invention.

FIG. 5 is a cross-sectional view at the time of a release step during molding by the upper mold of the present invention.

FIG. 6 is a half sectional view of an upper mold showing another embodiment.

7 is a half sectional view of a green compact formed by the upper die of FIG. 6;

FIG. 8 is a cross-sectional view showing an example of a green compact.

FIG. 9 is a cross-sectional view showing another green compact.

FIG. 10 is a sectional view of a powder filling step during molding by a conventional molding die.

FIG. 11 is a cross-sectional view of a powder moving process during molding by a conventional molding die.

FIG. 12 is a cross-sectional view of a pressing step during molding by a conventional molding die.

FIG. 13 is a cross-sectional view of a release step during molding by a conventional molding die.

FIG. 14 is a sectional view showing another conventional upper mold.

FIG. 15 is a sectional view showing a conventional problem.

[Explanation of symbols]

 35 Upper die 36 Die set 37 Fixed punch 40 First movable punch 41 Second movable punch 42 First cylinder 45 Second cylinder

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22F 1/00-8/00 B28B 3 / 00,5 / 00 B30B 11/00

Claims (2)

(57) [Claims] 1. A molding die for molding a green compact having different thicknesses in at least three places in the pressing direction under pressure, a fixed punch integrally attached to a vertically movable die set, and the fixed punch. A first movable punch disposed adjacent to the punch and capable of moving up and down in the die set with a stroke d; and a first movable punch adjacent to the first movable punch and shorter than the elevating stroke d of the first movable punch. A second movable punch that is arranged to be able to move up and down on the die set with a stroke e; and a second movable punch that is arranged between the die set and the first movable punch. A driving means for selectively driving the second movable punch; a biasing means for constantly biasing the second movable punch toward the die set; and a driving means disposed between the first movable punch and the second movable punch. , The first movable punch is in front From the die set stroke (d
-E) when the first movable punch is separated from the second
Characterized by comprising an engaging means for engaging with the movable punch of (1). 2. A green compact forming die for press-molding a green compact having different thicknesses in at least three places in a pressing direction, wherein a die set is provided in a vertically movable die set so as to be able to move up and down by a stroke d. 1 movable punch, and a second movable punch adjacent to the first movable punch and arranged to be able to move up and down the die set with a stroke e shorter than an elevating stroke d of the first movable punch, A third movable punch that is adjacent to the second movable punch and that can be moved up and down in the die set by a stroke f shorter than the elevating stroke e of the second movable punch; A driving means for selectively driving the first movable punch to an ascending position or a descending position, and driving means for constantly moving the second movable punch and the third movable punch to the die set side. Energize Biasing means, and the first movable punch is disposed between the first movable punch and the second movable punch, and the first movable punch is separated from the die set by a stroke (de) or more. Engaging means for engaging the second movable punch with the second movable punch, and the second movable punch is disposed between the second movable punch and the third movable punch. An engaging means for engaging the second movable punch with the third movable punch when the second movable punch is separated by a stroke (ef) or more.