JPH04202603A - Compacting method - Google Patents

Abstract

PURPOSE:To execute compacting in such a manner that the density of parts having different thickness is made uniform, at the time of compacting a molded body having a rotation symmetry shape to a symmetry axis and having different thickness by pressurization on powdery raw material, by using a punch having a specified structure. CONSTITUTION:At the time of compacting a molded body having a rotation symmetry shape to a symmetry axis as the center and having parts with different thickness in the radial direction by pressurization on raw material powder, the raw material powder is charged to the inside of a molding cavity 4a provided in a die of a lower assembled body 1 and is compacted by pressurization by the edge face of a lower punch 5 and the edge face of an upper punch 12 in an upper assembled body 2. At this time, because the upper punch 12 is provided with edge faces 24, 25 and 26 for forming a thick part, a thin part and a medium-sized part and the edge face 25 for forming a thin part is provided with a gate part 27 of compound grains, at the time of rotating and pressing the upper punch 12, a part of the powdery raw material in the thin part is fed to the space for forming the thick part or the medium-sized part, and the density of the raw material powder in each thick, thin and medium-sized part is made nearly equal, by which a green compact in which the density of the whole is uniform can easily be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a powder compacting method for forming a rotationally symmetrical powder compact.

2. Conventional technology 2. A solid powder material is filled between two punches in a forming hole formed in a die, and the solid powder material is pressurized and compressed by both punches to form a green compact. The powder compaction method has been known for a long time.

In such a powder compacting method, when the thickness of the powder compact in the punching direction differs locally, it is necessary to make the compressibility of each part constant in order to equalize the density of each part with different thickness.

For example, as shown in FIG. 12, the thickness of the solid powder material S in the pressing direction before compaction is A in the thick part, B in the middle part, and C in the thin part, On the other hand, when the thickness of the solid powder material S' in the pressing direction after compaction is a in the thick part, b in the middle part, and C in the thin part, In order to make the body density uniform, it is necessary to set A/a==B/1)=C/c,====--Equation 1.

However, when powder compaction is performed using a conventional integrated punch (single-acting punch), the compression length is constant, so Formula I cannot be satisfied, and the thickness or thinner part in the pressing direction is It is strongly compressed and becomes denser.

Therefore, conventionally, when forming green compacts with different thicknesses in the pressing direction, a double-acting punch that can press and compress the solid powder material individually for each portion of different thickness has been used. It was necessary to use it.

For example, as shown in FIG. 12, first to third lower punches 102 to 104, which can be raised and lowered individually, and first to third upper punches 105, which can be raised and lowered individually, are provided in a forming hole 101a formed in a die 10. - 107, the inner part is compacted by the first lower punch 101 and the first upper punch 105, the thin part is compacted by the second lower punch 103 and the second upper punch 106, and the thick part is compacted by the second lower punch 103 and the second upper punch 106. is compacted by the third lower punch 104 and the third upper punch +07.

[Problems to be Solved by the Invention] However, in a conventional powder compacting device equipped with a double-acting punch as shown in FIG. The cost will be high, ■ It will take time to replace mold tools such as gougs and punches, which will reduce work efficiency. ■ The rigidity of mold tools such as gouges and punches will decrease, resulting in frequent breakage and other malfunctions. There's a problem.

The present invention has been made in order to solve the above-mentioned conventional problems, and is a simple powder compacting method capable of compacting powder compacts having partially different thicknesses in the pressing direction with uniform density. The purpose is to provide a method.

[Means for Solving the Problem] In order to achieve the above object, the present invention presses and compresses a solid powder material with a punch to form a rotationally symmetrical shape with respect to an axis of symmetry and a thickness in the axial direction of the axis of symmetry. This is a powder compacting method for molding a powder compact with partially different thicknesses, in which a dam is provided on the batch surface that forms a thinner part in the direction of the symmetry axis of the powder compact, and the pressure is reduced during compaction. A punch equipped with a weir is rotated with the axis of symmetry of the powder as the rotation axis, and the weir part converts a part of the solid powder material that is thinner in the direction of the axis of symmetry into a part that is thicker in the direction of the axis of symmetry. To provide a powder compacting method characterized in that the powder is moved to form a compacted powder having a uniform density.

[Operations and Effects of the Invention] According to the present invention, when a solid powder material is compacted, as the notch rotates, the weir part creates a thinner part (hereinafter referred to as This is called the thin section)
A part of the solid powder material is moved to the surrounding area where the thickness in the pressurizing direction is thick (hereinafter referred to as the "thick interior"), so the density of the thin wall part is lowered, while the density of the thick wall part is reduced. be enhanced.

Therefore, by appropriately setting the shape of the dam or the rotation conditions of the punch, it is possible to make the density of the green compact uniform by using an integrated punch (single-acting punch).

And since the double-acting mechanism of the punch is not required, the die,
The operating mechanism of the punch and the like is simplified, equipment costs are reduced, and mold tools can be replaced quickly. Furthermore, since the rigidity of the punch is increased, failures such as breakage of the punch are reduced.

Two fruitless: Examples of the present invention will be specifically described below.

As shown in FIG. 1, the powder compacting device P is composed of a lower assembly 1 and an upper assembly 2. As shown in FIG.

A die 4 is fixed to the die holder 3 of the lower assembly l. A cylindrical molding hole 4a is formed in the die 4 and passes through the die 4 in the vertical direction, and a substantially cylindrical lower patch 5 is fitted into the molding hole 4a. Here, the upper end surface of the lower punch 5 is formed in a shape corresponding to the shape of the powder compact. Further, the lower punch 5 is fixed to a lower punch holder 7 attached to the upper surface of the lower bolster 6.

A mandrel 8 is fitted into a cylindrical hollow portion formed by penetrating the lower punch 5 in the vertical direction.
A lower ram 9 is provided for raising and lowering. Although not shown, the die holder 3 is connected to the lower punch holder 7 via a spring (which may be a pneumatic device or a hydraulic device) and is always urged upward.

On the other hand, the upper assembly 2 is provided with a substantially cylindrical upper patch 12 that can be inserted into the forming hole 4a of the die 4, and the upper patch 12 is fixed to an upper punch base 13. Here, the upper punch stand 13 is formed in the upper punch holder 17 and is fitted into an L substantially cylindrical recess 17a. Note that the upper punch holder 17 is attached to the upper bolster 16.

The upper punch table 13 is located within the recess 17a along its axis (
It can be rotated around the vertical line. Also,
The upper end surface of the upper punch table 13 is connected to a plurality of steel balls 14,
It is in contact with a pressure receiving plate 15 fixed to the upper punch holder 17. Therefore, the pressure receiving plate 15 can press the upper punch stand 13 (upper punch 12) downward while rotating it.

Further, a motor 18 is attached to the upper punch holder 17 via a motor holder 20, and a drive gear 21 is attached to the rotating shaft 18a of the motor 18.

This drive gear 21 meshes with the idle gear 22,
The idle gear 22 further meshes with a driven gear 23 provided on the outer periphery of the upper punch 12 near the upper end. At this moment, the upper punch 12 is rotationally driven by the motor 18 via the drive gear 21, the idle gear 22, and the driven gear 23.

As shown in FIG. 2, the tip of the upper punch 12 (lower end in FIG. 1) has a first end surface 24, a second end surface 25, and a third end surface in order from the outer circumferential side (left side in FIG. 2). 26 are formed. Here, the second end surface 25 is formed at a position that protrudes most toward the distal end, and the third end surface 26 is formed at the position where the second end surface 25
5, and the first end face 24 is formed at a position further set back from the second end face 26.

Due to the difference in the axial position of these end faces 24 to 26, a thick part 31a, a thin part 31b, and a medium part 31c are formed in the powder compact 31, respectively (see FIG. 9). .

A plurality of ring portions 27 having a height of about 1 to 1.5 mm are formed on the second end surface 25 of the second trowel. As will be explained later, as the upper punch 12 rotates, this dam part 27 transfers a portion of the solid powder in the thin part 31b (see FIG. 9) to the thick part 318.
and the middle wall portion 31c.

Below, basically referring to Figures 1 and 2, Figure 3.
We will explain the powder compaction method when forming a powder compact for the clutch hub G used in a manual transmission using a powder compaction device as shown in the figure. The powder compaction method will be explained using a sleeve member G' having a simple shape as shown in FIG.

■As shown in FIG. 6, a predetermined amount of solid powder material 3 is placed in the cavity formed by the circumferential surface of the forming hole 48 of the die 4, the outer circumferential surface of the mandrel 8, and the upper end surface of the lower punch 5.
Insert 1. At this time, the upper surface of the solid powder material 31 is located at the same height as the upper end surface of the die 4. Although not shown in detail, in this state, the die 4 (guitar holder 3) is urged upward by a spring, or its upward movement is stopped by a rod driven by a cam. ing.

■As shown in Figure 7, the die 4 (die holder 3) is unlatched by the rod (not shown), and the die 4 (die holder 3) is moved upward by the urging force of the spring (not shown). let At the same time, use the lower ram 9 to
is also moved upward by the same distance. At this time, since the lower patch 5 is stationary, it is relatively in the same state as if only the lower punch 5 had moved downward, and the lower patch 5 is formed by the die 4, mandrel 8, and lower punch 5. The cavity formed by the solid powder material 31 is elongated in the vertical direction.
The upper surface is lowered below the upper end surface of die 4 to prevent solid powder material 31 from flowing out of the cavity.

■As shown in Figure 8, stroke the upper punch 12 (upper bolster +6) downward (downward 1))
, insert the upper punch 12 into the forming hole 4a of the die 4. Here, the motor 18 is driven to rotate and the lower punch 18 is rotated until the tip (lower end) of the upper punch 12 comes into contact with the upper surface of the solid powder material 31.

■As shown in Fig. 9, the upper punch 12 is rotated and further stroked downward to remove the solid powder material 3.
1 is pressurized and compressed. At this time, basically, a thick inner portion 31a is formed in a portion corresponding to the first end surface 24 of the upper punch 12, and a thin wall portion 31b is formed in a portion corresponding to the second end surface 25.
is formed, and a medium-thickness portion 31 is formed in a portion corresponding to the third end surface 26.
c is formed. Since the second end surface 25 is provided with a plurality of weir parts 27, as the upper punch 12 rotates, a part of the solid powder in the thin part 31b is transferred to the thick part 31a or the middle part by the weir part 27. 31c. Here, if the dam part 27 is not provided, as described above, the density will be the highest in the thin part 31b, followed by the density in the middle part 31c, and the density in the thick part 31a will be the lowest. However, in this case, due to the action of the weir part 27, a part of the solid powder in the thin wall part 31b is distributed to the middle wall part 3 at a predetermined distribution ratio.
1c and the thick part 31a, each part 31a
, 3 lb, and 31c have approximately the same density. In addition, various conditions such as the length of each weir part 27, the stroke position where the upper punch 12 starts rotating or the stroke position where the rotation stops are set so that the density of each part 318 of the solid powder material 318° 31b, 31c is made uniform. , is of course preferably set in advance.

[F] As shown in FIG. 10, after the rotation of the upper punch 12 is stopped at a predetermined stroke position, the solid powder material 31 is further pressurized to increase the overall density. In this way, a uniform and high-density green compact 31 is formed.

■As shown in FIGS. 11(a) and 11(b), after the compaction is completed, the die 4 (die holder 3) is lowered with a rod (not shown) until it comes into contact with the lower punch holder 7, and Lower ram 9 lowers mandrel 8. At this time, the powder compact 31 is exposed above the upper surface of the die 4. Thereafter, the green compact 31 is taken out using the fingers 32.

Although not shown in detail, the Finoka 32 works in conjunction with the press and uses a 102-dimensional transfer movement.
The compacted powder body 31 is taken out.

As described above, according to the present invention, a green compact with uniform density can be formed using an integrated punch with a simple operating mechanism.

In addition, in this embodiment, only the upper punch 12 is rotated by providing the weir part 27, or the difference in wall thickness is large.
If the density of the green compact cannot be made sufficiently uniform just by rotating the upper punch 12, the lower patch 5 may be provided with a weir section and rotated in the same manner as the upper punch 12. good.

[Brief explanation of the drawing]

FIG. 1 is an explanatory elevational cross-sectional view of a powder compacting device used in the powder compacting method according to the present invention. 2 is a partially cross-sectional perspective explanatory view of the upper punch of the powder compacting device shown in FIG. 1. FIG. FIG. 3 is a perspective explanatory view of a clutch hub manufactured by the powder compacting method according to the present invention. 4 is a perspective explanatory view of a sleeve member that is a simplified version of the clutch hub shown in FIG. 3. FIG. 5 is an explanatory elevational cross-sectional view of the sleeve member shown in FIG. 4. FIG. FIG. 6 is a schematic elevation cross-sectional view of the powder compacting apparatus shown in FIG. 1, showing a state in which the same powder material is charged into the cavity. FIG. 7 is a view similar to FIG. 6 showing the die and mandrel moved upward. Figure 8 shows the upper punch beginning to be inserted into the forming hole of the die.
7 is a diagram similar to FIG. 6 showing two states; FIG. FIG. 9 is a diagram similar to FIG. 6 during pressurization and compression of the solid powder material. FIG. 1O is a diagram similar to FIG. 6 at the end of pressurization and compression of the solid powder material. FIGS. 11(a) and 11(b) are a schematic plan view and a schematic elevation cross-sectional view, respectively, of the powder compacting device at the time of taking out the powder compact. FIG. 12 is an explanatory elevational cross-sectional view of the main part of a conventional powder compacting device equipped with a double-acting punch. P - powder compaction device, G - clutch hub, l - lower assembly, 2 - upper assembly, 4 die, 4a forming hole, 5 - lower punch, 12 upper punch, 18 - motor, 31 - Solid powder material (green compact), 31a --- Thick wall part, 31b
Thin part, 31c medium part.

Claims (1)

[Claims] (1) A powder compaction method in which a solid powder material is pressurized and compressed with a punch to form a compact that is rotationally symmetrical with respect to an axis of symmetry and has partially different thicknesses in the axial direction of the axis of symmetry. Therefore, a dam is provided on the punch surface that forms the thinner part in the direction of the axis of symmetry of the powder compact, and the punch with the dam is provided with the dam formed using the axis of symmetry of the compact as the rotation axis during compaction. By rotating, a part of the solid powder material in the thinner part in the symmetrical axis direction is moved by the weir part to the thicker part in the symmetrical axis direction, so that a green compact with uniform density is formed. A powder compaction method characterized by: