JPS63220940A - Forging method - Google Patents

Abstract

PURPOSE:To better the uniformity of a metal structure by preventing an inner part crack by inclining the rolling reduction face of die at specific angle in the case of reducing the diameter of the material to be forged in an axial shape by subjecting to a rolling reduction by a die. CONSTITUTION:A forging is effected by die by arranging at equal intervals in the four directions of orthogonal direction for the axial direction of the material 1 to be forged. In this case those which have the rolling reduction face inclining at an angle delta (2 deg..7 deg.) for the vertical face in the rolling reduction direction of the anvil are used. Dies 2a-2d are moved in the centripetal direction simultaneously from the orthogonal four directions for the axial direction of the material 1 to be forged to subject the material 1 to be forged to rolling reduction. Then the dies 2a-2d are simultaneously pulled in to rotate the material 1 to be forged in an arrow mark A direction and the dies 2a-2d are again moved in the centripetal direction simultaneously from the four parts in the orthogonal direction for the axial direction to effect rolling reduction. By repeating this the axial cogged roll stock having uniform metal structure is obtd.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to rolling down a shaft-shaped forged material from multiple directions perpendicular to the axial direction using an anvil simultaneously. The present invention relates to a forging method used to reduce the diameter (including tapering) of a material by swaging.

(Prior Art) Conventionally, when reducing the diameter of a ring-shaped forged material by swaging by simultaneously rolling down a ring-shaped forged material from multiple directions perpendicular to the axial direction, for example, four directions, using an anvil, for example, As shown in FIG.
, 2b.

2c and 2d, the shaft-shaped forged material 1 is held by a forged material holding device (not shown), and the anvils 2a to 2d are first inserted from four directions perpendicular to the axial direction of the forged material 1. 2d in the centripetal direction, and then the anvils 2a to 2d are simultaneously drawn in the centrifugal direction, and then the forged material 1 is moved at an angle (θ) in the direction of arrow A in FIG. ), and then the anvils 2a to 2 are rotated again from four directions perpendicular to the axial direction of the forged material 1.
d in the centripetal direction, and then the anvils 2a to 2d are simultaneously retracted in the centrifugal direction, and then the forged material 1 is moved in the direction indicated by the arrow A in FIG.
The anvil 2 is rotated by the same angle (θ) in the direction.
For each reduction by a to 2d, the angle (θ) of the forged material 1 is
The material to be forged 1 is gradually reduced in diameter by swaging by repeating one round of rolling.

(Problems to be Solved by the Invention) However, with such conventional forging methods, especially when forging difficult-to-work materials such as superalloys, a There are problems in that internal cracks may occur and the uniformity of the metal structure may be poor.

(Purpose of the Invention) This invention was made by focusing on the above-mentioned conventional problems, and even when forging difficult-to-work materials such as superalloys, internal cracks are difficult to occur, and the metal structure is It is an object of the present invention to provide a forging method that achieves sufficiently good uniformity and allows the material to be forged to be reduced in diameter or tapered.

[Structure of the Invention] (Means for Solving the Problems) The forging method according to the present invention involves simultaneously rolling down a shaft-shaped forged material from multiple directions perpendicular to the axial direction, for example, from four directions, using an anvil. When reducing the diameter (including tapering) of the material to be forged by swaging, the anvil is formed at an angle of 2° to 7°, more preferably 3° to 6°, with respect to the vertical plane in the rolling direction of the anvil. This is characterized by the use of a rolling surface that is inclined within a range.

As mentioned above, the present inventor has discovered that in the conventional forging method of rotating the forged material 1 by a predetermined angle (θ) as shown in FIG. Various studies were conducted on the reasons why internal cracks tend to occur at a depth of approximately 173 radii from the surface during forging of materials.

In the conventional forging method, as shown in Fig. 6, the material of the forged material 1 before deformation (indicated by the 0 mark in Fig. 6)
However, during deformation by the anvils 2a to 2d, the surface area of the forged material 1 rotates in the direction of rotation during forging (in the direction of the arrow in Fig. 6).
At the same time, at about 1/3 depth from the surface of the forged material 1, it flows in the opposite direction to the direction of rotation during forging (also shown in Figure 6). ) was confirmed by analysis of the cross-sectional fiber flow, and by repeating the reduction and rotation at each angle (θ) as described above, a , a large accumulated shear strain is generated (see the curve of the inclination angle (δ) Oo of the rolled surface in Fig. 1).
Therefore, it has been found that when forging difficult-to-work materials such as superalloys, internal cracks tend to occur at a depth of about 1/3 radius from the surface.

In addition, in the conventional forging method, as shown in FIG. 3, the anvils 2a to 2d are made of gold! 112c (2a.

2b, 2d) having an inclination angle of 0° with respect to the vertical plane in the rolling direction (direction of arrow B in Fig. 3), that is, the rolling surface 2 is perpendicular to the rolling direction. In this case, It has been found that the contact surface with the forged material 1 is biased toward the entry side of the forged material 1, and the contact surface on the exit side is reduced. Then, as shown in FIG. 4, the direction in which the anvil 2c (2a, 2b, 2d) is rolled down (arrow B
If the rolling surface 2 is inclined by a certain angle of inclination (δ) with respect to the vertical plane of the forged material 1, the contact surface with the forged material 1 will be approximately equal to the entrance and exit sides of the forged material 1. The results of various experiments have confirmed that the same can be achieved, and it has been confirmed that the shear strain accumulated inside the forged material 1 can be considerably reduced. Subsequently, various experiments were conducted, and it was found that if the inclination angle (δ) of the anvils 2a to 2d with respect to the vertical plane in the rolling direction was less than 2 degrees, a sufficient effect was obtained in reducing the shear strain accumulated inside. I can't help it.

On the other hand, even if the inclination angle (δ) is made larger than 7°, the effect of reducing shear strain will not be improved much, and the unfavorable component force for the anvils 2a to 2d will increase, so the inclination angle (δ) is 2°~
It has been confirmed that the angle is preferably in the range of 7°, more preferably in the range of 3° to 6°.

(Example) Corrosion-resistant and heat-resistant superalloy (Inconel 718) was used as the material to be forged.
An ingot with an outer diameter of 340 mmφ was selected.

After soaking the forged material, as shown in FIG. Forging was performed according to steps 2a to 2d.

In this embodiment, the anvils 2a to 2d are those in which the inclination angle of the rolling surface 2 in the longitudinal direction (direction perpendicular to the plane of the paper in FIGS. 3 and 4) changes stepwise from the center part to the outer part. In addition, the inclination angle (δ) of the rolling surface 2 in the transverse direction (vertical direction in FIG. 3) is the same as that of the anvils 2a to 2d.
0 with respect to the vertical plane in the rolling direction (four arrow directions in Figure 3)
0 (conventional), the inclination angle (δ) of the rolling surface 2 in the transverse direction (vertical direction in FIG. 4) is
2 with respect to the vertical plane in the rolling direction (four directions of arrows in Figure 4)
One with an angle of 4°, and one with an angle of 6° were used.

And each anvil 2a to 2 for each of these inclination angles (δ)
d, the shaft-shaped forged material 1 is held by a forged material holding device (not shown), and the anvils 2a to 2d are first moved from four directions perpendicular to the axial direction of the forged material 1.
The forged material 1 is rolled down by simultaneously moving them in the centripetal direction, and then the anvils 2a to 2d are simultaneously retracted in the centrifugal direction. In the case of the embodiment of the present invention), the angle (O
; In this case, the anvil 2a is rotated by θ=13°), and then the anvil 2a is rotated again from four directions perpendicular to the axial direction of the forged material 1.
2d are simultaneously moved in the centripetal direction, the forged material 1 is rolled down, and then the anvils 2a to 2d are simultaneously retracted in the centrifugal direction, and then the forged material 1 is moved in the direction shown by the arrows in FIGS. 3 and 4. Similarly, the angle (θ; in this case, θ=
By repeating the process of rotating the forged material 1 by an angle (θ = 13°) each time the anvils 2a to 2d are rolled by an angle of 13° (swaging), the outer diameter is 165 mm. A axially forged and drawn material was obtained.

The results of investigating the relationship between the position from the surface of the shaft-shaped forged material obtained in this way and the amount of shear strain accumulated are as shown in Fig. 1, and the inclination angle (δ) of the rolled surface 2 is 0. The shear strain accumulation amount showed a fairly large value when As shown in Fig. 2, the maximum shear strain accumulation does not decrease significantly even when the inclination angle (δ) of the rolling surface 2 is made larger than 7°, and is rather affected by the increase in component force. It was confirmed that it became visible.

When we examined the cross section of the shaft-shaped forged material in the direction perpendicular to the axis after forging, we found that when using conventional anvils 2a to 2d with the inclination angle (δ) of the rolling surface 2 set to 00, the forging Internal cracks had occurred at a depth of about 1/3 radius from the surface of the material, but the inclination angle (δ) of the rolling surface 2 was changed to 2', 4'.
When using the anvils 2a to 2d according to the embodiments of the present invention shown in 6° and 6°, no cracks were generated inside the forged material, almost no surface flaws were observed, and the entire area of the forged material was Satisfactory results were obtained in which the metal structure was uniform and good throughout.

[Effects of the Invention] As explained above, according to the forging method of the present invention, a shaft-shaped to-be-forged material is simultaneously rolled down with an anvil from multiple directions perpendicular to the axial direction. When reducing the diameter by swaging, as the anvil,
Since we used an anvil with a rolling surface inclined in the range of 2° to 7° with respect to the vertical plane in the rolling direction of the anvil,
Even when forging difficult-to-work materials such as superalloys, internal cracks are unlikely to occur, and the uniformity of the metal structure is sufficiently good to achieve thinner or tapered diameters of the forged material. This has the great effect of making it possible.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the position from the surface of the material to be forged and the amount of accumulated shear strain after forging and stretching, and Figure 2 is the inclination angle (δ) of the rolling surface of the anvil after the material to be forged is forged and stretched. Fig. 3 is a side explanatory view showing the contact situation with the material to be forged in a conventional anvil, Fig. 4 is a graph showing the relationship between
The figure is an explanatory side view showing the state of contact between the anvil and the material to be forged according to the embodiment of the present invention, and FIG. An explanatory diagram of the forging method that performs forging and elongation! FIG. 86 is an explanatory diagram showing a cross-sectional fiber flow of a forged material by forging. 1... Material to be forged, 2a to 2d... Anvil, 2... Reduction surface of the anvil, δ... Inclination angle of the anvil reduction surface. Patent Applicant Daido Steel Co., Ltd. Representative Patent Attorney Yutaka Oshio Figure 1 Figure 2 Figure 3 Figure 4 0' -Start

Claims (1)

[Claims] (1) When reducing a shaft-shaped forged material from multiple directions perpendicular to the axial direction with an anvil simultaneously to reduce the diameter of the forged material by swaging, as the anvil,
A forging method characterized by using an anvil having a rolling surface inclined in the range of 2° to 7° with respect to a vertical plane in the rolling direction.