JPH038858B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a forging method when manufacturing a metal ring by forging.

[Conventional technology]

For example, relatively large ring-shaped objects used under high temperature and high stress conditions as parts of jet engines and gas turbines are manufactured from heat-resistant steel or nickel-based alloys, and the manufacturing process is usually as follows. That's right. That is, the ingot is made into a circular or polygonal, for example octagonal, cross-section with a hammer or hydraulic press (forging), cut into the required length (so-called cutting), and the resulting cylinder or polygon is forged in the axial direction. Then place it on the hole stand and punch out the center by pushing in the punch (drilling).
After enlarging the hole (hole enlarging) and adjusting the height (flat pressing or flat hammering), the hole is enlarged and shaped again to produce a product. To expand the hole, insert the core into the drilled material, place both ends on a stand called a pedestal, press the ring in the radial direction with a hydraulic press, etc., and rotate the core. This is carried out by repeating the pressing operation and forging the entire circumference. Flat pressing is performed by placing the ring on the anvil and pressing it in the axial direction. Forging is carried out through the above-mentioned processes, and it goes without saying that the quality of these processes governs the mechanical properties of the product. Furthermore, it is well known that making the crystal grain size as fine as possible is preferable for the characteristics of the product. When the conventional ring forging method is reexamined from this perspective, it is by no means satisfactory. The hole enlarging process is performed while rotating the core metal with a manipulator or the like, which is inefficient. Therefore, as long-time operations are required, there is a large difference in the temperature at the end of processing between the ring where processing begins and the end of processing, which tends to cause uneven grain size, making it difficult to avoid variations in product characteristics. .

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ring forging method that solves the above-mentioned problems and can more efficiently produce ring products with superior properties than those achieved by the prior art.

[Means to solve the problem]

The ring forging method of the present invention achieves this objective.
Prepare a ring material with dimensions that allow for the reduction in thickness due to rolling, place it on the anvil so that one end surface is in contact with it, and place it in the diametrical direction of the ring with respect to the other end surface, so that the cross section is approximately A semicircular forging tool that protrudes toward the ring is compressed in the axial direction by rotating the ring around the center of the ring, gradually moving the contact position between the forging tool and the ring, and compressing it in the axial direction. and diameter expansion at the same time. As the anvil, a disk turner often used for metal forging is suitable. ``A shape that protrudes toward a ring whose cross section is approximately semicircular'' is representative of the semicircular or semicircular shape shown in the figure, but also includes not only semi-ellipses but also polygons with rounded corners. When strongly pressed towards the ring, it does not have a shape that presses it flatly, but a cross-sectional shape that goes into the ring so as to push it left and right.

[Effect]

If the above steps are explained with reference to the drawings, the first
2 and 3, a ring material 10 with slightly enlarged holes is placed on a disc turner 1, and a semi-cylindrical forging tool 2 is placed in the diameter direction of the ring. It is pressed downward by the hydraulic press 3. Pull up the forging tool 2,
Rotate the disc turner 1 a little and then press it downward again. While repeating this operation and rotating the disk turner 1 by 180 degrees, the height of the ring 10 decreases and its inner and outer diameters expand. The principle of this is as shown in Figure 4. The circular ring shown in Figure A is deformed as shown in Figure B by the initial pressure of the forging tool, and the pressed part is crushed and the forging tool It stretches slightly in the longitudinal direction, and the remaining part is pushed out a little in the direction perpendicular to the forging tool. By repeating this sequentially,
As shown in Figure C, the inner and outer diameters are expanded throughout the ring, resulting in hole enlargement. In short, in the ring forging method of the present invention, in the series of forging steps described above, hole enlarging using a core metal and a stand is reduced compared to the conventional method, and instead of this, flat pressing is performed using a special forging tool. This can be said to improve the efficiency of hole expansion. The ratio of conventional hole expansion and special flat pressing, which is a feature of the present invention, to be combined depends on the material, dimensions and shape of the ring to be forged, the degree of forging required, etc. Depending on the situation, the optimum conditions can be found through many experiments. For example, for Ni-based heat-resistant alloys,
If suitable values are given for the dimensions of the material at the time of hole expansion, it is recommended to prepare a material that is approximately twice the height and 1.2 times the cross-sectional area of the final product ring.

【Example】

Inconel-718 (Ni-based alloy) having a composition meeting the following specifications was melted and ring-forged according to the steps shown in FIG. C: 0.08% or less Si: 0.35% or less Mn: 0.35% or less P: 0.015% or less S: 0.015% or less Ni: 50.00-55.00% Cr: 17.00-21.00% Mo: 2.80-3.30% Co: 1.00% or less Cu: 0.30% or less Al: 0.20 to 0.80% Ti: 0.65 to 1.80% Nb+Ta: 4.75 to 5.50% B: 0.006% or less Fe: Residual Product size (mm) is as follows: Inner diameter Outer diameter Thickness (A ) 250×350×30 (B) 350×450×50 A was processed according to methods No. 1 to 5 shown in Table 1, and B was processed according to methods No. 6 and No. 7. Among these, No. 5 is a comparative example in which upsetting was performed to the height of the final product according to the prior art, and the others are examples of the present invention. In both cases, the heating temperature is 1120℃ and the final temperature is 950℃.
That's all. Note that No. 4 and No. 7 were shaped and finished by being reheated to 1050° C. after flat pressing. The forged ring was treated under the following conditions: 950°C x 1 hour, water cooled, then held at 718°C x 8 hours, then ramped up at a cooling rate of 56°C/hour, held at 621°C x 8 hours, then air cooled. A piece was taken. The grain size of each test piece was determined. The results are shown in Table 2, and are consistent with the observation results of the macrostructure using corrosion photographs. Lapture testing was conducted according to the AMS5663C standard. Test temperature: 649°C Stress: 10,000 psi Test piece: combination type After 90 hours, the test was increased by 5,000 psi and tested until rupture. The results are shown in Table 3. In addition, a room temperature tensile test and a high temperature tensile test (649°C) were also conducted, and both results far exceeded the standard values.

【table】

【table】

[Table] * Broken at punch part

【Effect of the invention】

When using the forging method of the present invention, there is no need to operate a heavy core metal with a manipulator as in the conventional method.
Since the disk turner can be rotated by 180 degrees, it can be rolled down one round, making the flat pressing process extremely efficient. This shortens the time required for forging, which means that the processing start temperature can be lower than before. This, combined with the fact that a special forging tool is used during flat pressing to create a strong reduction that extends to the inside of the material, is highly effective in making the grain size finer after solution treatment. In this way, a forged ring is obtained which has significantly improved mechanical properties, especially yield strength and rupture elongation. Needless to say, finer grain structure reduces variations in product characteristics.

[Brief explanation of the drawing]

1 to 3 are views for explaining the situation in which the ring forging method of the present invention is carried out, in which FIG. 1 is a plan view, FIG. 2 is a side view, and FIG.
FIG. FIG. 4 is a plan view of a ring for explaining the principle of hole expansion by the ring forging of the present invention, where A is the ring material and B is a view after one press of the forging tool. , and C indicate the steps performed twice. Figure 5 shows the steps of the ring forging method of the present invention.
A diagram showing a cross section of a material, including: cutting,
The following stages are shown: Upsetting, Drilling, Expanding, Pushing flat, Finishing. 1... Disc turner, 2... Forging tool, 3...
...Hydraulic press, 10...Ring material.

Claims (1)

[Claims] 1. In a method for forging a metal ring, a ring material with dimensions that allow for reduction in thickness due to rolling is prepared, and the ring material is placed on an anvil so that one end surface of the material is in contact with the anvil, A forging tool that is located in the diametrical direction of the ring, has an approximately semicircular cross section, and has a shape that protrudes toward the ring with respect to the other end surface, and rotates the ring around the center of the ring. A ring forging method that is characterized by compressing the ring in the axial direction and expanding the diameter at the same time by applying strong pressure while gradually moving the contact position with the ring. 2. The forging method according to claim 1, in which a disk turner is used as an anvil, and the position of the forging tool relative to the ring is moved by rotation of the disk turner. 3. The forging method according to claim 1, in which the above-mentioned processing is performed on a ring material that is approximately twice as thick as the final product and has a cross-sectional area that is approximately 1.2 times as large.