JPH05279703A - Powder molding method and its device - Google Patents

Abstract

PURPOSE:To approximate the packing density of powder at the time of supplying the powder to uniformity as far as possible in the case of molding an annular powder molding. CONSTITUTION:The powder set state attained by supplying the powder P to an annular space formed of a die 6 and a core rod 20 and the subsequent compression molding of the powder P are premised. The core rod 20 is positioned lower than the position of the core rod 20 at the time of the powder set state before the power supply under such premises and the core rod 20 is positioned to the position of the core rod 20 in the powder set state after the subsequent powder supply.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a powder molding method and apparatus.

[0002]

2. Description of the Related Art A powder molding method is disclosed in Japanese Utility Model Laid-Open No. 63-7130.
As shown in the publication, an annular space (powder set space) is formed by a die and a core rod, powder is supplied to the annular space, and then the powder is compression-molded to obtain an annular molded product. There is something I did.

[0003]

However, in the above method, when the powder is supplied, the powder is supplied from above into the annular space formed by the die and the core rod. And the core rod, the powder supply port must be narrow, and the powder supply causes powder adhesion, frictional force, etc. in the powder layer in the annular space, At a certain portion, a cross-linking phenomenon occurs in which a supporting force sufficient to support the powder pressure above that occurs, and thus the packing density of the powder tends to vary. Therefore, if the powder in this state is compression molded after this,
A compression molded product having a non-uniform density is produced.
The present invention has been made in view of the above circumstances, and an object thereof is to make the packing density of the powder at the time of powder supply as uniform as possible when forming an annular powder molded product.

[0004]

In order to achieve the above object, in the present invention (the first invention), a powder is set in an annular space formed by a die and a core rod, and then the powder is set. In the powder molding method of compressing and molding powder, the core rod is located at a retracted position from the position of the core rod in the powder set state before the powder is supplied, and the core rod is provided after the powder is supplied and before the compression molding. Is positioned at the position of the core rod in the powder set state. With the above configuration, since the core rod is retracted from the position in the powder set state at the time of powder supply, the powder supply port is enlarged and is not restricted by the narrow gap between the core rod and the die.
When supplying the powder, the crosslinking phenomenon of the powder can be suppressed. Therefore, after this, the core rod is advanced and positioned at the position in the powder set state, but at this time, the packing density of the powder does not vary.

Further, in order to achieve the above-mentioned object, in the present invention, a through hole is provided in the die, and the core rod and the die are arranged with the core rod inserted into the through hole. In the powder molding apparatus, which cooperates with each other to form an annular powder setting space, the core rod can be moved back and forth with respect to the through hole, and the core rod can move the powder setting space before powder feeding. Is set to a retreat position with respect to the position where the powder is formed, and is set to a position where the powder setting space is formed after the powder is supplied.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. First, a powder molding apparatus for carrying out the method according to this embodiment will be described with reference to FIGS. In the powder molding apparatus 1, as shown in FIG. 1, a fixed plate 2 is arranged, and a cylindrical support member 3 is erected on the fixed plate 2. A cylindrical lower punch 4 is provided on the upper end surface of the support member 3, and the upper end surface is a flat surface.

A plurality of guide rods 5 are slidably passed through the fixed plate 2 so as to extend in the vertical direction, and dies 6 are fixed to the upper ends of the respective guide rods 5. A yoke plate 7 is fixed to the lower end of each guide rod 5. The die 6 is arranged horizontally, and its upper surface is a flat surface. On the upper surface of the die 6, a powder supply box 8 is placed as shown in FIG. The lower surface of the powder supply box 8 is opened, and the powder P such as iron powder is stored inside the powder supply box 8. A through hole 9 is formed in the die 5. The through hole 9 penetrates the die 6 in the vertical direction, and the lower punch 4 is fitted in the through hole 9 so as to be relatively displaceable.

The yoke plate 7 is arranged in a horizontal state, and an apparatus such as an air cylinder (not shown) having a lifting and cushioning function is linked to the yoke plate 7.

On the yoke plate 7, there are shown in FIGS.
As shown in FIG. 3, an elevating mechanism 10 is provided. In this lifting mechanism 10, a cylindrical screw member 11 is fixed on the yoke plate 7, a male screw is engraved on the outer peripheral surface thereof, and a female screw is engraved on the inner peripheral surface thereof. There is.
An adjust spacer 12 is screwed onto the outer periphery of the screw member 11, and a core cylinder 14 is integrally connected to the adjust spacer 12 via a bolt 13. Accordingly, when the adjust spacer 12 is rotated with respect to the screw member 11, the core cylinder 14 moves up and down, and the position of the core cylinder 14 can be adjusted.

On the other hand, a slide holder 15 is screwed onto the inner circumference of the screw member 11. A guide member 16 is fixed to the upper surface of the slide holder 15, and an upper end portion of the guide member 16 is fitted into the core cylinder 14 so as to be relatively displaceable. As a result, the core cylinder 14 and the guide member 16 form the working space 17.

A core piston 18 is slidably fitted in the working space 17. The core piston 18 defines an operating space 17 into two chambers, and a compressed fluid supply / discharge means 19 is connected to each chamber.

The core piston 18 is the core cylinder 1.
4 has a protruding portion 18a slidably passing therethrough, and a core rod 20 is connected to the protruding portion 18a. The core rod 20 has a shaft portion 21 and a head portion 22. The shaft portion 21 penetrates through the fixed plate 2 and the support member 3 so as to be vertically displaceable, and the lower end portion thereof is fixed to the projecting portion 18 a of the core piston 18. The head 22 is fixed to the upper end of the shaft 21, the head 22 is slidably fitted to the inner circumference of the lower punch 4, and the upper surface of the head 22 is a flat surface. There is.

An upper punch 23 is provided in an upper region of the lower punch 4 so as to be movable up and down, as shown in FIG.
The upper punch 23 has a cylindrical shape, and as the upper punch 23 descends, the inner periphery of the upper punch 23 is the core rod 2
It can be fitted to the outer periphery of the head portion 22 of 0, and the lower end surface thereof can abut on both upper surfaces of the lower punch 4 and the die 6. Incidentally, 24 is a stopper bolt and 25 is a sleeve.

Next, the method according to this embodiment using the powder molding apparatus 1 will be described with reference to FIGS. First,
As a preparatory state before molding, as shown in FIG.
However, the upper surface of the core rod 20 is set so that its upper surface is located above the upper surface of the lower punch 4, and the upper surface of the head portion 22 of the core rod 20 is set flush with the upper surface of the lower punch 4.

When this preparation state is completed, as shown in FIGS. 3 and 4, the powder supply box 8 moves on the die 6, and the through hole 9 of the die 6 is inserted into the lower part of the powder supply box 8. Positioned to fit in. As a result, the powder P in the powder supply box 8 is allowed to pass through the through holes 9 above the lower punch 4 and the head 22.
Will be filled inside. At this time, the supply port of the powder P becomes the through hole 9, and the supply port serves as the side surface of the head 22 and the through hole 9.
It will be enlarged compared to the case where there is a gap between the inner peripheral surface. Therefore, the crosslinking phenomenon of the powder P can be surely avoided, and the packing density of the powder P becomes uniform.

Next, as shown in FIG. 5, the head 2 of the core rod 20 is maintained while the powder supply box 8 is maintained in the position shown in FIG.
2 is raised so that its upper surface is flush with the upper surface of the die 6. As a result, excess powder P for molding is pushed back into the powder supply box 8, and at this time, the force for pushing back does not act on the lateral side, so the die 6 and the head 2
A uniform packing density of the powder P in the annular space 26 formed by 2 and 2 is maintained. Then, after this, the powder supply box 8 moves to the original position, and at that time, the powder P existing on the upper surface of the die 6 and the upper surface of the head 22 is removed.

Next, as shown in FIG. 6, the upper punch 23
, And the powder and the die 6 in the annular space 26 are pressed downward to compress the powder P in the annular space 26. As a result, an annular molded product 27 is obtained. At this time, since the yoke plate 7 is linked to the air cylinder or the like, the die 6 also descends with the compression molding of the powder P.

Next, when the compression molding of the powder P is completed, the upper punch 23 returns to the original position, while the upper surfaces of the die 6 and the head 22 are the upper surfaces of the lower punch 4, as shown in FIG. It is descended so that it becomes flush with. On the basis of this, the molded product 27 is slid on the die 6 and carried out, and is transferred to the next sintering step. After this, dice 6
The state of FIG. 3 is restored, and the apparatus stands by for the next compression molding.

Therefore, as described above, in the preparation state of FIG. 3, the powder supply port is enlarged to prevent the crosslinking phenomenon,
Since it is possible to make the filling state of the powder (see FIG. 5) in the annular space 26 thereafter uniform, the molded product 27 of FIG.
Will be of high quality.

[0020]

As described above, according to the first and second inventions, in the case of forming an annular powder molded article,
The packing density of the powder at the time of powder supply can be made as uniform as possible.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a powder molding apparatus according to an embodiment.

FIG. 2 is an enlarged view of a lower portion of FIG.

FIG. 3 is a diagram showing a preparation state in which the supply of powder is started.

4 is an operation state diagram showing an operation from the state of FIG.

5 is an operation state diagram showing an operation from the state of FIG.

FIG. 6 is an operation state diagram showing an operation from the state of FIG.

FIG. 7 is an operation state diagram showing an operation from the state of FIG.

[Explanation of symbols]

 1 Powder Forming Device 6 Die 9 Through Hole 20 Core Rod 26 Annular Space P Powder

Claims (2)

[Claims] 1. A powder forming method in which a powder is supplied to an annular space formed by a die and a core rod, and then the powder is compression-molded. Before the powder is supplied, the core rod is in the powder set state. Of the core rod at a retracted position, and after the powder supply and before the compression molding, the core rod is
A powder molding method, characterized in that the core rod is positioned at the position of the powder set state. 2. A powder in which a through hole is provided in a die, and a core rod is provided in the through hole so that the core rod and the die cooperate with each other to form an annular powder set space. In the molding apparatus, the core rod can be moved back and forth with respect to the through hole, and further, the core rod is located at a retracted position from a position where the powder setting space is formed before the powder is supplied, and after the powder is supplied. The powder molding apparatus is set so as to be positioned at a position forming the powder setting space.