JPH04344845A - Method and device for forging formation - Google Patents

Abstract

PURPOSE:To prevent the generation of cracking flaw by executing forging while applying pressure in a reverse direction to a fluidized direction to a forging raw material fluidized in a forming hole. CONSTITUTION:The forging raw material is charged into the forming hole 16 in a lower die 2, and by lowering an upper die 1, pressurized-compressing is executed. The forging raw material is plastically deformed and extruded in the forming hole 8, and a pressing punch 10 is pushed up to compress a coil spring 15. Spring pressure of the coil spring 15 suppresses the fluidity of the forging raw material fluidized in the forming hole 8, and tension stress worked between an inner face side and a center part side in the forming hole 8 is restrained and the generation of the cracking flaw 21 in the forming product 22 is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging method and an apparatus therefor.

0002

2. Description of the Related Art Conventionally, for example, as shown in FIG. 7, a circular forging material 54 is mounted in a circular forming hole 53 of a lower die 52 of a forging forming apparatus equipped with an upper die 51 and a lower die 52. Then, as shown in FIG. 8, the upper mold 51 is lowered and the cylindrical protrusion 55 protruding from the lower part of the upper mold 51 is inserted into the molding hole 53 of the lower mold 52. The forged material 54 is compressed under pressure between the upper die 51 and the lower die 52, and the forged material 54 is extruded into a circular forming hole 56 formed in the upper die 51 and plastically deformed along the forming hole 56 to form a cylindrical shape. There is one in which a molded product 58 having a protrusion 57 is forged.

0003

[Problems to be Solved by the Invention] In the conventional method, when the forging material 54 is pressurized and plastically deformed, the forging material 54 flowing in the forming hole 56 of the upper die 51 and the inner surface of the forming hole 56 are separated. There is a frictional force between the molded hole 5 and
Tensile stress acts between the outer circumferential side and the center side of the forged material 54 flowing inside the forged material 6. This tensile stress is applied to a difficult-to-process material (for example, material: Al-20Si) as the forging material 54.
When a certain extrusion ratio ((diameter D1 2 /
Diameter D2 of the protrusion 57 of the molded product 58 Under 2), there is a limit to the relationship between the diameter D2 of the protrusion 57 of the molded product 58 and the protrusion length L of the protrusion 57. If the protrusion length L of the protrusion 57 is larger than the diameter D2, there is a problem in that the protrusion 57 develops cracking defects in the circumferential direction.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a forging method and apparatus designed to prevent the occurrence of crack defects in the protruding parts of the molded product.

[0005]

[Means for Solving the Problems] The technical means according to claim 1 taken by the present invention to achieve the above-mentioned object is to pressurize a forging material charged in a mold to transform the forging material into a mold. In the forging method of forging by plastically deforming the material along the forming hole, the forging material is forged while applying pressure in a direction opposite to the flow direction of the material flowing in the forming hole.

[0006] The technical means according to claim 2 also provides a forging forming device for forging by pressurizing a forging material charged into a mold and plastically deforming the forging material along the forming hole of the mold. The method further comprises a pressure applying means for applying pressure in a direction opposite to the flowing direction of the forged material to an end face in the flow direction of the forged material flowing in the forming hole during forging of the forged material.

[0007]

[Operation] To forge the forged material 20 to form the molded product 22, the forged material 20 is charged into a mold, and the charged forged material 20 is pressurized. Then, the forging material 20 is plastically deformed and extruded into the forming hole 8 of the mold to be forged. In the present invention, during forging of this forged material 20,
Pressure in a direction opposite to the flow direction of the forging material 20 is applied to the forging material 20 flowing in the forming hole 8 by the pressure applying means 5. The pressure applied by this pressure applying means 5 is
Forming hole 8 The forming hole 8 of the forged material 20 flowing inside acts to cancel out the tensile stress that acts between the inner surface side and the center side, and prevents the occurrence of cracking defects in the molded product 22 due to the tensile stress. .

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. 1 and 2 show a first embodiment of the present invention. In the figures, 1 is an upper die, 2 is a lower die, and the upper die 1 is a ram ( (not shown), and the lower die 2 is fixedly attached to the bed of the hammer device or press device.

The upper mold 1 has a punch 3 attached to the ram.
, a die 4 attached to the punch 3 and a pressure applying means 5. A cylindrical protrusion 6 is formed in the center of the lower surface of the punch 4 to project downward, and a die mounting hole 7 is formed in the lower part of the punch 4 upward from the center of the lower surface of the protrusion 6. , this die mounting hole 7
The die 4 is attached from below. A circular forming hole 8 is formed in the center of the die 7 so as to pass through it in the vertical direction, and a through hole 9 having a smaller diameter than the die mounting hole 7 and larger than the forming hole 8 is formed in the upper part of the punch 4. is formed so as to communicate with the forming hole 8 from the upper end surface of the punch 3,
A substantially cylindrical presser punch 10 is slidably inserted into the forming hole 8 through the through hole 9. This presser punch 1
A collar 11 that is movable up and down in the through hole 9 is provided at the upper end of the 0 to protrude radially outward. Also, the through hole 9 of the punch 3
A spring storage member 13 is fixed to a counterbore 12 formed at the upper end, and a spring storage hole 14 smaller in diameter than the through hole 9 is formed in the spring storage member 13 from the bottom surface upward. A compression coil spring 15 is fitted into the spring storage hole 14, and the lower part of the coil spring 15 is movable in and out of the storage hole 14 and is in contact with the upper end surface of the presser punch 10. The presser punch 10 and the coil spring 15
etc. constitute the pressure applying means 5.

[0010] In the upper part of the lower mold 2, a circular forming hole 16 into which the protrusion 6 of the upper mold 1 is inserted is formed downward from the upper surface. Note that 18 is a knockout pin, and 19 is a lifting platform of a lifting device for raising and lowering the knockout pin 18. In the above configuration, the forged material 2
To forge 0, first, the upper die 1 is positioned at the initial position shown in FIG. At this time, the collar 11 of the presser punch 10 is in contact with the upper end surface of the die 4, and substantially the entire presser punch 10 is inserted into the forming hole 8 of the die 4. Next, the forged material 20 preformed into a circular block shape is charged into the forming hole 16 of the lower mold 2 , and then the upper mold 1 is lowered and the protrusion 6 of the punch 3 of the upper mold 1 is inserted into the lower mold. The forging material 20 is inserted into the forming hole 16 of the upper die 1 and the lower die 2.
Pressure is compressed between. Then, the forging material 20 is plastically deformed, and the forging material 20 is extruded into the forming hole 8 of the die 4 of the upper die 1 and also into the forming hole 16 of the lower die 2.
The remaining space is filled, and as shown in FIG. 1, a molded product 22 having a protrusion 21 is formed by forging. and,
When the forged material 20 is extruded into the forming hole 8 of the die 4 of the upper die 1, the presser punch 10 is pushed up by the forged material 20 flowing upward in the forming hole 8, and the coil spring 15 is compressed. Due to the spring pressure of the coil spring 15, pressure is applied to the forging material 20 flowing in the forming hole 8 via the presser punch 10 in a direction opposite to the flow direction, and the forging material 20 is forged while being applied with this pressure. It looks like this. Due to this spring pressure, the forming hole 8
The tensile stress acting between the inner surface and the center side of the forming hole 8 of the forged material 20 flowing therein is suppressed, and cracking defects are prevented from occurring in the protrusion 21 of the molded product 22.

Next, specific experimental examples of forging using the above-mentioned apparatus are shown in Table 1 below. As the forging material 20, the material is Al-
Rapidly solidified aluminum alloy powder consisting of 20Si,
The material was pressurized at a temperature of 400° C. and a pressure of 9 tonf/cm 2 to form a circular block having a compact density of 94% of the true density. The forging conditions were a temperature of 400°C, a ram speed of 40 spm, and a forming load of 300.
ton and extrusion ratio of 11, and oil-based graphite is used as a lubricant. In Table 1, the ○ mark indicates that there is no cracking defect, and the × mark indicates that a cracking defect has occurred.The value of the spring pressure of the coil spring is the value at the end of forging, and the value of the spring pressure before forging is The pressure is set to zero. Further, L indicates the protruding length of the protruding portion 21 of the molded product 22,
D indicates the diameter of the protrusion 21 of the molded product 22.

0012

[Table 1]

FIGS. 3 and 4 show a second embodiment, in which the upper mold 1 consists only of punches. In addition, the lower die 2 includes an upper die 23, an intermediate die 24, and a lower die 2.
These dies 23, 24, 25 are fixed by a die holder 26. The upper die 23 has a molding hole 27 vertically penetrating into which the protrusion 6 of the upper mold 1 is inserted, and the middle die 24 has a molding hole 28 communicating with the molding hole 27 halfway from the upper end in the vertical direction. The molded hole 2 is formed from the middle part to the lower end.
A guide hole 29 communicating with 8 is formed. Further, a presser punch 10 is fitted into the molding hole 28 of the intermediate die 24 so as to be slidable in the vertical direction, and the presser punch 10 and the molding hole 28
A compression coil spring 15, which together with the presser punch 10 constitutes the pressure applying means 5, is interposed between the bottom surface and the bottom surface. Further, the presser punch 10 includes a guide hole 29 of the intermediate die 24.
A guide rod 30 is provided which is slidably inserted into and guided in the vertical direction. FIG. 3 shows the state before forging, and in the same figure, 20 is a forged material, and FIG. 4 shows the state after forging, and in the same figure, 22 is a molded product.

FIGS. 5 and 6 show a third embodiment, and to explain the difference from the second embodiment, the lower die 2 includes an upper die 31 and a lower die 32. 31 is formed with a molded hole 33 that is vertically penetrating. The lower die 32 includes a die housing 35 having a vertically penetrating mounting hole 34 and a molding hole 33 of the upper die 31.
A die ring 36 having an inner diameter that is approximately the same as the die ring 36 and fixedly fitted into the mounting hole 34 of the die housing 35, a mounting base 37 fitted and fixed inside the lower part of the mounting hole 34 of the die housing 35, and the mounting base 37. A counter punch 39 has a protrusion 38 projecting upward from the center of the counter punch 39, and an annular molding hole 40 is formed between the protrusion 38 of the counter punch 39 and the die ring 36. The presser punch 10 has a ring shape and is fitted into the molding hole 40 of the lower die 32 so as to be vertically slidable, and the coil spring 15 is attached to the presser punch 10.
and the mounting base 37 of the counter punch 39.
It is stored inside.

In the above embodiment, pressure may be applied by fluid pressure or the weight of a weight instead of the spring, and the space between the upper mold and the lower mold may be used as a molding hole. The present invention may be applied to various modifications. Further, the forged material 20 may be made of extruded metal powder or melted material. Generally, when forging is performed using a forging material made by compacting metal powder, the metal powder is cold compression molded to form a preform, which is then sintered to create a forging material. If the bond between the powders is not strengthened by sintering, cracking defects are likely to occur during forging, but in the present invention, even if the sintering step is omitted, the occurrence of cracking defects can be suppressed.

[0016]

Effects of the Invention According to the present invention, in a forging material that is pressurized and plastically deformed along a forming hole of a mold, a pressure in a direction opposite to the flow direction of the flowing portion is applied to a portion of the forging material that flows inside the forming hole. Since the forging material is forged while adding a It is possible to prevent cracking defects from occurring in the part.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a forging forming apparatus showing a first embodiment in a state after forging.

FIG. 2 is a side cross-sectional view of the forging forming apparatus showing the first embodiment in a state before forging.

FIG. 3 is a side cross-sectional view of a forging forming apparatus showing a second embodiment in a state before forging.

FIG. 4 is a side cross-sectional view of the forging forming apparatus according to the second embodiment in a state after forging.

FIG. 5 is a side cross-sectional view of a forging forming apparatus showing a third embodiment in a state before forging.

FIG. 6 is a side cross-sectional view of the forging forming apparatus according to the third embodiment in a state after forging.

FIG. 7 is a side sectional view of a conventional forging forming apparatus in a state before forging.

FIG. 8 is a side sectional view of a conventional forging forming apparatus in a state after forging.

[Explanation of symbols]

1 Upper mold 2 Lower mold 5 Pressure applying means 8 Molding hole 10 Presser punch 15 Coil spring 20 Forged material 22 Molded products

Claims (2)

[Claims] 1. A forging method in which a forging material charged into a die is pressurized to plastically deform the forging material along a forming hole of the die for forging, wherein the forging material flows within the forming hole. A forging forming method characterized by forging the forged material while applying pressure in a direction opposite to the flow direction. 2. A forging forming apparatus that pressurizes a forging material charged into a mold to plastically deform the forging material along the forming hole of the mold for forging, during forging of the forging material, A forging forming device comprising pressure applying means for applying pressure in a direction opposite to the flow direction of the forging material to an end face in the flow direction of the forging material flowing in a forming hole.