JP2503484B2 - Forging method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is forging a shaft-shaped material to be forged at the same time by an anvil from a plurality of directions perpendicular to the axial direction. Material is made smaller by swaging (including taper)
The present invention relates to a forging method used for forming.

(Prior Art) Conventionally, when a forging material having an axial shape is swollen at the same time by simultaneously pressing down a plurality of directions perpendicular to the axial direction, for example, four directions with an anvil, For example, as shown in FIG. 5, four anvils 2a, 2 arranged at 90 ° intervals at right angles to the axial direction of the material 1 to be forged.
Using b, 2c, 2d, the shaft-shaped forging material 1 is held by a not-shown forging material holding device, and first, anvil is placed from four directions perpendicular to the axial direction of the forging material 1. 2a to 2d are simultaneously moved in the centripetal direction to reduce the forging material 1 and then the anvils 2a to 2d are simultaneously drawn in the centrifugal direction, and then the forging material 1 is angled in the direction of arrow A in FIG. By rotating (θ), the anvils 2a to 2d are simultaneously moved in the centripetal direction from the four directions perpendicular to the axial direction of the forging material 1 again to reduce the forging material 1, and then again. After the anvils 2a to 2d are simultaneously pulled in the centrifugal direction, the forging material 1 is also rotated by the same angle (θ) in the direction of arrow A in FIG. The material 1 is rotated by an angle (θ), which is repeatedly rolled and rolled to forge (sue) By managing), it had to be gradually reduced in diameter to be forged material 1.

(Problems to be solved by the invention) However, in such a conventional forging method, when a soft workable material such as a superalloy is forged, at a depth of about 1/3 radius from the surface, There is a problem that internal cracks may occur and the metallographic structure may be inferior in uniformity.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems. Even when performing forging of a difficult-to-process material such as a superalloy, internal cracks are less likely to occur, and a metallographic structure It is an object of the present invention to provide a forging method that can make the material to be forged sufficiently thin and achieve a reduction in diameter or a taper.

[Structure of the Invention] (Means for Solving Problems) A forging method according to the present invention is a method in which an axially shaped material to be forged is simultaneously pressed down from a plurality of directions perpendicular to the axial direction, for example, four directions by an anvil. After the reduction, the forged material is rotated around the axis by a predetermined angle and simultaneously reduced again by the anvil, and the simultaneous reduction by the anvil and the rotation of the forged material by the predetermined angle are repeated to reduce the diameter of the forged material by swaging. In forming (including tapering), an anvil having a pressure lower surface inclined at an angle of 2 ° to 7 °, more preferably 3 ° to 6 ° with respect to a vertical plane in the rolling direction of the anvil. A plurality of pressing surfaces are provided so as to be farther from the axis of the forging material on the entrance side in the rotation direction of the forging material and closer to the axis of the forging material on the exit side in the rotation direction of the forging material. To be rolled down from the same direction In which are characterized.

As described above, the present inventor has made 1
In the conventional forging method of rotating a predetermined angle (θ) for each rolling reduction as shown in Fig. 5, especially when forging a difficult-to-process material such as a superalloy, a depth of about 1/3 radius from the surface is used. By the way, various investigations have been repeated on the causes of internal cracks.

And in the conventional forging method, as shown in FIG.
When the material of the material 1 to be forged (indicated by a circle in FIG. 6) before deformation is deformed by the anvils 2a to 2d, in the region on the surface layer side of the material 1 to be forged, the rotation direction during forging (arrow A in FIG. 6). direction)
Simultaneously with the flow direction (indicated by ● in Fig. 6), and at the depth of about 1/3 from the surface of the material 1 to be forged, it flows in the direction opposite to the rotation direction during forging (also in Fig. 6). (Indicated by ●) was confirmed by analysis of cross-section fiber flow,
By repeating the reduction and rotation for each angle (θ) as described above, a large accumulated shear strain is generated at a depth of about 1/3 from the surface of the forging material 1 (first Due to the inclination angle (δ) 0 ° curve of the pressure face in the figure), internal cracking is likely to occur at a depth of about 1/3 radius from the surface when forging difficult-to-process materials such as superalloys. I found a thing.

In the conventional forging method, the anvils 2a-2d are
As shown in the figure, the anvil 2c (2a, 2b, 2d) is rolled down (3rd
The direction having an inclination angle of 0 ° with respect to the vertical plane (direction of arrow B in the figure), that is, the pressing surface 2 perpendicular to the rolling direction is used. In this case, the contact surface with the forging material 1 is It was found that the forged material 1 was largely offset to the entrance side and the contact surface on the exit side was reduced. Then, as shown in FIG. 4, the pressure lower surface 2 inclined by a certain inclination angle (δ) with respect to the vertical plane of the anvil 2c (2a, 2b, 2d) in the rolling direction (direction of arrow B in FIG. 4) is formed. The pressing surface 2 of the forging material 1 is provided further on the inlet side of the forging material 1 in the rotation direction A and further from the axis of the forging material 1 and on the outlet side of the forging material 1 in the rotation direction A. It was confirmed as a result of various experiments that the contact surface with the forging material 1 can be made substantially the same on the inlet side and the outlet side of the forging material 1 by making the orientation closer to the shaft center. It was confirmed that the shear strain accumulated inside the can be considerably reduced. Then, after various experiments were conducted, if the inclination angle (δ) of the anvils 2a to 2d with respect to the vertical plane in the rolling direction is less than 2 °, a sufficient effect can be obtained in reducing the shear strain accumulated inside. On the contrary, even if the inclination angle (δ) is made larger than 7 °, the effect of reducing the shear strain is not improved so much, and the unfavorable component force for the anvils 2a to 2d is increased. It was confirmed that the inclination angle (δ) is preferably in the range of 2 ° to 7 °, more preferably in the range of 3 ° to 6 °.

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

After soaking the material to be forged, as in the case shown in FIG. 5, anvils arranged at equal intervals in four directions perpendicular to the axial direction of the material to be forged 1, that is, 90 °. Forging was performed by 2a to 2d.

In this embodiment, as the anvils 2a to 2d, the pressure surface 2 is used.
Of which the inclination angle in the longitudinal direction (the direction perpendicular to the paper surface of FIGS. 3 and 4) gradually changes from the central portion to the outer portion, and the lateral direction of the pressure lower surface 2 (see Three
The inclination angle (δ) in the vertical direction of the figure is 0 ° with respect to the vertical plane of the anvils 2a to 2d in the rolling direction (direction of arrow B in FIG. 3) (conventional one), The inclination angle (δ) in the lateral direction (vertical direction in FIG. 4) is 2 ° with respect to the vertical plane of the anvils 2a to 2d in the rolling direction (direction of arrow B in FIG. 4), but at 4 °. Some and those at 6 ° were used.

And each anvil 2a-2d for each of these inclination angles (δ)
The pressure surface 2 is farther from the axis of the forged material 1 on the inlet side in the rotational direction of the forged material 1 and closer to the axial center of the forged material 1 on the outlet side in the rotational direction of the forged material 1. And the axial forging material 1 is held by a forging material holding device (not shown). First, the anvils 2a to 2d are simultaneously centered from four directions perpendicular to the axial direction of the forging material 1. The material to be forged 1 by moving it in the direction
After pulling 2a to 2d simultaneously in the centrifugal direction, forged material 1
At a predetermined angle (θ; in this case θ = 13 in the direction of arrow A in FIG. 3 (conventional case) and FIG. 4 (case of the present invention).
)) And then again move the anvils 2a to 2d simultaneously in the centripetal direction from four directions perpendicular to the axial direction of the forge 1 to press down the forge 1 and then again anvil 2a. ~ 2d are simultaneously drawn in the centrifugal direction, and then the forged material 1 is also rotated in the direction of arrow A in Figs. 3 and 4 by a predetermined angle (θ; in this case also θ = 13 °), and thus the anvil 2a ~ A shaft-shaped forged material having an outer diameter of 165 mm was obtained by repeating forging (swaging) the step of rotating the forged material 1 by a predetermined angle (θ = 13 °) for each reduction by 2d. .

The result of examining the relationship between the position from the surface of the axially forged material thus obtained and the amount of accumulated shear strain is as shown in FIG. 1, and the inclination angle (δ) of the pressure lower surface 2 is 0. The shear strain accumulation amount showed a considerably large value at ゜, but the shear strain accumulation amount gradually decreased by increasing the inclination angle (δ) of the pressure surface to 2 °, 4 °, 6 °. As shown in FIG. 2, the maximum amount of accumulated shear strain does not decrease so much even if the inclination angle (δ) of the pressure surface 2 is larger than 7 °. It was confirmed that it could be seen.

Then, the cross section of the axially forged material after the forging was examined in the direction perpendicular to the axis, and when the conventional anvils 2a to 2d in which the inclination angle (δ) of the pressure surface 2 was 0 ° were used, The internal cracks were formed at a depth of about 1/3 radius from the surface of the drawn material, while the inclination angle (δ) of the pressure surface 2 was 2 °, 4 °, 6 °. When using the anvils 2a ~ 2d of the example, no cracks were generated inside the wrought material, almost no surface defects were found, and a uniform and good metallographic structure was obtained over the entire wrought material. We were able to obtain the satisfactory result that it is the one that exists.

[Effects of the Invention] As described above, according to the forging method according to the present invention, the forging material having the axial shape is simultaneously pressed by the anvil from a plurality of directions perpendicular to the axial direction, and the forging is performed after the pressing. When the material is rotated about the axis by a predetermined angle and simultaneously pressed down again by the anvil, the simultaneous pressing by the anvil and the rotation of the forged material at a predetermined angle are repeated to reduce the diameter of the forged material by swaging, As the anvil, one having a pressure lower surface inclined in a range of 2 ° to 7 ° with respect to a vertical surface in the rolling direction of the anvil is used, and the pressure lower surface of the forging material is on the inlet side of the forging material in the rotation direction. Since it is located farther from the axis and closer to the axis of the material to be forged on the exit side in the direction of rotation of the material to be forged, it is possible to carry out simultaneous pressing from multiple directions. Internal crack even when doing Is less likely to occur, and the uniformity of the metal structure can be made sufficiently good, and the diameter or taper of the forged material can be reduced, which is a significant effect.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the position of the forged material from the surface after the forging and the amount of accumulated shear strain, and FIG. 2 is the inclination angle (δ) of the pressure surface of the anvil after the forging of the forged material. And a graph showing the relation between the maximum shear strain accumulation amount, FIG. 3 is a side explanatory view showing the state of contact with the forged material in the conventional anvil, and FIG.
FIG. 5 is a side view showing the state of contact with the material to be forged in anvil according to the embodiment of the present invention, and FIG. 5 is a drawing of an axial forging material simultaneously from the four directions perpendicular to the axial direction by the anvil. Fig. 6 is an explanatory view of a forging method of performing forging by stretching, and Fig. 6 is an explanatory view showing a cross-sectional fiber flow of a forged material by forging. 1 …… Forged material, 2a ～ 2d …… Anvil, 2 …… Pressing surface of anvil, δ …… Inclination angle of anvil pressing surface.

Claims (1)

(57) [Claims] 1. An axial forging material is simultaneously rolled down from a plurality of directions perpendicular to the axial direction by an anvil, and after rolling, the forging material is rotated around a shaft center by a predetermined angle and simultaneously repressed by an anvil. When the forging material is reduced in diameter by swaging by repeating simultaneous reduction by the anvil and rotation of the forging material at a predetermined angle, the anvil is 2 ° to 7 ° with respect to a vertical plane in the rolling direction of the anvil. A pressure-reducing surface inclined in the range of 0 ° is used. The pressure-reducing surface is farther from the axis of the forged material on the inlet side in the rotational direction of the forged material and on the outlet side in the rotational direction of the forged material. A forging method characterized by simultaneously reducing from a plurality of directions in a direction closer to the forging material axis.