JPH0994699A - Powder compacting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of seizure on a punch and to uniformize the compact density of forming goods by improving the rigidity of a lower side punch and making the deformation of the lower side die caused by the pressing pressure less. SOLUTION: A lower side punch 4 is formed by relatively movably arranging an outside lower punch 3 having a forming face 3a corresponding to the shape of an external circumference face and a bottom face of a step part 1b and the external circumference face 1a continuing to the lower part of this step part in a stepped circular shape part 1 having a step on the external circumference of circular cylinder face, and an inside lower punch 2 having a forming face 8a corresponding to the shape of the bottom face except the above, and further the inside lower punch 2 is movably arranged. An upper punch 5 having a forming face 5a corresponding to the shape of the upper face of the part 1 is arranged opposite this lower side punch 4 movably in the axial direction while pressing the part 1 from the upper side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder press device for powder compacting a stepped circular part having a step portion on the outer periphery of a cylindrical surface whose center line extends in the vertical direction.

[0002]

2. Description of the Related Art Generally, when manufacturing a powder sintered part or the like, it is first necessary to compress the powder into a predetermined shape by a powder press machine. In the case of a circular part, the outer peripheral surface is formed by a cylindrical die, and the upper and lower end surfaces are formed by the compression operation of the upper and lower punches. In the case of a shape having a portion, in the structure of the powder pressing apparatus that has been generally adopted in the past, there was a risk that seizure would occur in part of the punch due to repeated press molding.

That is, in the case of a circular part having a stepped portion with a different diameter on the outer circumference of the cylindrical surface, the punches on the lower side corresponding to each stepped portion in order to make the compression density uniform in each portion of the molded product. Is divided into a cylindrical shape, and the outer portion of the lower punch moves according to the length of the lower punch as the lower punch is compressed.
The ratio of the height filled with the powder before the compression and the height of the product after the compression is equalized in each step (see, for example, Japanese Utility Model Laid-Open No. 55-13973).

However, in the case of the above flange-shaped step portion, when the step thickness is thin, that is, the amount of protrusion in the diametrical direction due to the diameter change is small, the thickness of the punch member at this portion is also thin and the rigidity is low, and the pressing process The compressive pressure acts on the punch member so as to spread it outward, and the punch member is deformed, so that the outer peripheral portion thereof slides relatively to the inner peripheral surface of the outer die in a state of strong pressure contact. By repeating this press molding, sliding streaks may be generated in the vertical direction on the contact surfaces of the two, and finally seizure may occur.

As another molding apparatus for a stepped circular part, for example, as disclosed in Japanese Utility Model Publication No. 60-127330, a shape corresponding to a flange-shaped stepped portion of the circular part is provided on the outer die. There is a method in which a stepped die having a notch is formed, and the movable upper punch is pressed against the fixed lower punch to perform press forming.

However, in the case where the stepped die is provided and the lower punch is fixed as described above, the problem of seizure of the lower punch as described above is reduced, but the compression density in each part of the molded product is reduced. It becomes difficult to make it uniform. In other words, the compression operation is performed only from the upper punch, the internal pressure rise is different between the flange portion and the main body portion in relation to the movement of the die, the powder moves inside, and finally the powder becomes uniform as a whole. It becomes difficult to obtain the compressed density.

[0007]

In view of the above circumstances, the present invention improves the rigidity of the lower punch and reduces the deformation due to the pressing pressure to prevent the occurrence of seizure in the punch and to make the punch uniform in each part. It is an object of the present invention to provide a powder pressing device capable of obtaining a compressed density.

[0008]

The powder pressing apparatus of the present invention, which has solved the above-mentioned problems, has an outer periphery of the outermost step portion in a stepped circular part having a step portion on the outer periphery of a cylindrical surface whose center line extends in the vertical direction. An outer lower punch having a surface, a bottom surface of the outermost peripheral step portion, and a forming surface corresponding to the shape of the outer peripheral surface continuing to the lower portion of the outermost peripheral step portion; and an inner lower punch having a forming surface corresponding to the shape of the bottom surface other than the above. Is relatively movable and an inner lower punch is movably arranged to form a lower punch, and the outer periphery of the outer lower punch is supported by a guide plate. The upper punch having a molding surface corresponding to the shape of the upper surface of the above is disposed so as to be axially movable with respect to the lower punch.

[0009]

As described above, according to the present invention, the outer lower punch has a thick wall and has a high rigidity, the deformation due to the press pressure is reduced, and the occurrence of sliding seizure on the outer peripheral surface is prevented. It is possible to perform good compaction molding for a long period of time. Further, by performing the press molding while moving the inner lower punch, even in the case where the outer lower punch has a step portion, the internal pressure difference is small and the flow of the powder is suppressed to make the final compression density uniform. You can

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded cross-sectional view of a main part of a powder pressing apparatus in a pressed state of a circular part.

The stepped circular part 1 to be powder compacted has a flange portion 1b (outermost step portion) protruding to the upper outer periphery of an outer peripheral surface 1a as a cylindrical surface whose center line extends in the vertical direction,
A through hole 1c is formed in the central portion, the upper end surface 1d is substantially flat, and the lower end surface 1e is provided with a protrusion 1f projecting in the axial direction on the central portion side.

In the molding of the above-mentioned component 1, a lower punch 4 composed of an inner lower punch 2 and an outer lower punch 3 for molding the bottom surface portion and the peripheral surface portion of the component 1 and a lower end molding surface 5a by pressure operation from above. The upper punch 5 for forming the upper end surface 1d of the component 1 and the core rod 6 for forming the through hole 1c at the central portion on the outer peripheral surface are performed.

The inner lower punch 2 includes a fixed lower punch 7 having an upper end molding surface 7a for molding the bottom surface of the bottom projection 1f of the component 1, and an inner peripheral surface and a lower end surface 1e for molding the peripheral surface of the projection 1f. The inner lower punch 8 has each molding surface 8a of the upper end surface to be molded.

The outer lower punch 3 has a molding surface 3a for molding the outer peripheral surface 1a of the component 1 and the bottom surface and peripheral surface of the flange portion 1b. That is, this molding surface 3a
Is composed of an inner peripheral molding surface corresponding to the outer peripheral surface 1a of the component 1, and a notch portion 9 forming a concave molding surface corresponding to the bottom surface and the peripheral surface of the flange portion 1b.

The core rod 6, the fixed lower punch 7, the inner lower punch 8 and the outer lower punch 3 are arranged concentrically in order from the inner side to the outer side. The outer lower punch 3 and the outer lower punch 3 are provided so as to be vertically slidable in the axial direction. A ring-shaped guide plate 10 that supports the outer peripheral surface of the outer lower punch 3 is slidably disposed outside the outer lower punch 3.

FIG. 2 shows the supporting structure of the punches 2 to 4, and FIG. 2 shows a powder filling state before pressing. The fixed lower punch 7 of the inner lower punch 2 has a pipe-shaped lower end portion supported by a cylindrical fixed base 13 via a first plate 12 and is held in a fixed state. The core rod 6 penetrating the inside of the fixed lower punch 7 penetrates the first plate 12, is connected to and supported by the core 14 in the fixed base 13, and is slidably operated when the component 1 is ejected.

On the other hand, the lower ends of the inner lower punch 8 and the outer lower punch 3 each have a second plate 15 at the lower end.
Also, it is connected to and supported by the bottom platen 17 and the standard platen 18 via the third plate 16.
The guide plate 10 is further supported by the top platen 19 on the outer peripheral portion. Further, the upper punch 5 has an upper end connected to and supported by the press mechanism 20.

The bottom platen 17 and the standard platen 18 are regulated in the descending position during pressing by a press stop (not shown), and the press stop releases the regulation after pressing and shifts to an eject operation. Has been done. Further, the bottom platen 17 and the standard platen 18 are each provided with an elevating cylinder (not shown) to be moved up and down to a predetermined position, and are urged upward during pressing to respond to the pressing operation of the upper punch 5. It moves down.

Further, in order to supply the powder P, a powder feeding shoe 21 which is in contact with the upper surface of the top platen 19 and slidable in the lateral direction is provided.

The operation of the above configuration will be described. First, when the powder P is supplied for performing the powder compaction, as shown in FIG. 2, the core rod 6, the inner lower punch 8, the outer lower punch 3, and the guide plate 10 (top platen 19) are moved to the raised position. Then, the tip end portion of the core rod 6 and the upper end surface of the outer lower punch 3 and the upper end surface of the guide plate 10 (top platen 19) are flush with each other, and the powder feeding shoe 21 is moved on this surface to move the outer peripheral portion of the core rod 6 to the outer peripheral portion. The space P to be formed is filled with the powder P. At that time, the shape of the space portion is set to be enlarged in the vertical direction so that a predetermined compression ratio can be obtained in each portion with respect to the product size of the component 1.

Next, the upper punch 5 is lowered by the pressing force of the press mechanism 20, the lower end molding surface 5a thereof contacts the upper surface of the powder P, and further descends to start the press molding. With the lowering of the upper punch 5, the outer lower punch 3 and the inner lower punch 8 are lowered to a position corresponding to the product shape and stopped by a press stop not shown, and the upper punch 5 is also moved to a predetermined position corresponding to the product shape. Then, the powder P is compressed to the size of the component 1 as shown in FIG.

Subsequently, the eject operation is started, and the outer lower punch 3 and the inner lower punch 8 are released from their press stops and further lowered by a cylinder (not shown). As a result, as shown in FIG. 3, the outer lower punch 3 and the inner lower punch 8 are pulled out from the peripheral surface of the component 1, and the core rod 6 is pulled out from the inner surface of the component, and the inner lower punch 8, the outer lower punch 3 and the upper ends of the core rod 6 are pulled out. The height is adjusted to the height of the upper end of the fixed lower punch 7, and the upper punch 5 is lifted to remove the mold of the component 1. The demolded and molded component 1 is taken out by, for example, the lateral feeding operation of the powder feeding shoe 21.

Although powder compaction is sequentially performed by repeating the above operation, the outermost step of the component 1, that is, the peripheral surface and the bottom surface of the flange portion 1b, and the outer peripheral surface 1 continuous with this.
Since the punch for forming a is integrally formed with the outer lower punch 3 having the cutout portion 9, conventionally, a thin lower punch corresponding to the step width of the flange portion 1b is configured to slide up and down and the guide plate 10 is formed. The seizure with the die that is equivalent to the above has occurred, but by increasing the thickness of the outer lower punch 3 and increasing its rigidity, the deformation due to the press pressure is small and the occurrence of seizure is avoided in advance. are doing. Further, by performing the press molding while moving the inner lower punch 8 of the lower punch 4, the internal compression density can be made uniform.

In the above embodiment, the stepped circular component 1 has the lower surface protrusion 1f in addition to the flange portion 1b. Therefore, the inner lower punch 2 is fixed to the lower punch to form the protrusion 1f. 7 and inner lower punch 8
However, in the case of the shape without the projection 1f, the inner lower punch 2 may be constituted only by the movable inner lower punch 8. Further, when the number of steps of the component 1 is further increased, it is necessary to increase the number of movable inner lower punches 8 in accordance with the number of steps. Further, the component 1 requires the core rod 6 because the through hole 1c is formed at the center, but in the case of a solid shape, the core rod 6 becomes unnecessary. On the other hand, formation of irregularities such as splines or key grooves on the inner and outer peripheral surfaces of the component 1 can also be performed by changing the design of each molding surface.

[Brief description of drawings]

FIG. 1 is an exploded cross-sectional view of a main part of a powder pressing apparatus according to an embodiment of the present invention in a pressed state.

FIG. 2 is a cross-sectional view of the main parts of the powder pressing apparatus before pressing.

FIG. 3 is a sectional view of the main part in the eject state.

[Explanation of symbols]

 1 circular part 1a outer peripheral surface 1b flange 2 inner lower punch 3 outer lower punch 3a forming surface 4 lower punch 5 upper punch 5a forming surface 6 core rod 7 fixed lower punch 7a forming surface 8 inner lower punch 8a forming surface 9 notch 10 guide plate 20 Press mechanism

Claims (1)

[Claims] 1. A powder press device for powder compacting a stepped circular part having a step portion on the outer periphery of a cylindrical surface whose center line extends in the vertical direction, the outer peripheral surface of the outermost step portion of the part and the outer peripheral surface of the step portion. The outer lower punch having a forming surface corresponding to the shape of the outer peripheral surface following the bottom of the outermost peripheral step and the lower portion of the outermost peripheral step, and the inner lower punch having a forming surface corresponding to the shape of the bottom surface other than the above The inner lower punch is movably disposed to form a lower punch, and the outer periphery of the outer lower punch is supported by a guide plate,
With respect to the lower punch, an upper punch having a molding surface corresponding to the shape of the upper surface of the component is arranged from the upper side so as to be capable of pressurizing and moving in the axial direction with respect to the lower punch. Powder pressing equipment.