JP2002307125A - Forging method of hard-to-work ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forging method of a hard-to-work ring in which surface cracks are hardly generated in a corner part, etc., of an inside diameter surface during the hole expansion or hole expansion shaping in forging the hard-to-work ring 1. SOLUTION: In this forging method of the hard-to-work ring, a dummy ring 2 is inserted in the inside diameter surface of the hard-to-work ring 1, and hole expansion or hole expansion shaping is performed after simultaneously heating both the dummy ring and the hard-to-work ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forging a difficult-to-work ring, and more particularly to forging or expanding a difficult-to-work ring having poor hot workability such as a duplex stainless steel or a Ni superalloy by forging. The present invention relates to a forging method for a difficult-to-process ring.

[0002]

2. Description of the Related Art Conventionally, when a ring is manufactured by free forging, as shown in FIG. 2, the ring is formed by forging and cutting a steel ingot and cutting the material to a required size, a thick disk-shaped process. It is manufactured through an upsetting process, a drilling process for drilling, a hole expanding and shaping (hole expanding and shaping) process for expanding and shaping holes. Then, the hole expanding and shaping step by the forging described above is performed as shown in FIG.
The metal core 3 is put into the heated ring 6 to be processed as shown in (1), and the core metal is placed on the two metal core bases 4 so that the ring to be processed is between the two metal core bases 4. This was done by forging at 5.

[0003] The hole expansion and shaping in the conventional hole expanding and shaping step have no problem in a material having good hot workability, but in a difficult-to-work ring having poor hot workability, the forging temperature range of the material itself. When the material temperature of the inner diameter surface (also referred to as inner surface, inner surface, etc.) decreases due to contact with the core metal, the temperature becomes lower than the forgeable temperature range. Had surface cracks.

[0004] Therefore, difficult-to-work rings with poor hot workability, such as duplex stainless steel and Ni superalloy, have been subjected to mechanical cutting to expand the holes without performing the hole expanding and shaping step in the forging. However, hole enlargement by mechanical cutting has disadvantages such as long processing time and waste of a lot of material.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forging a difficult-to-machine ring in which a surface crack does not occur at a corner portion or the like of an inner diameter surface in hole expansion or hole-expansion shaping by forging the difficult-to-machine ring. Is the subject.

[0006]

In order to solve the above-mentioned problems, in the method for forging a difficult-to-machine ring according to the present invention, a dummy ring is inserted into the inner surface of the difficult-to-machine ring, and both are heated at the same time. To perform hole expansion or hole expansion shaping. Further, in the forging method for a difficult-to-machine ring of the present invention, the dummy ring is manufactured from a material having a better hot workability than the difficult-to-machine ring.

[0007]

According to the method for forging a difficult-to-machine ring of the present invention, a dummy ring is inserted into the inner surface of a difficult-to-machine ring such as a duplex stainless steel or a Ni superalloy, and both are heated at the same time and then forged or expanded by forging. Since shaping is performed, the inner diameter surface of the difficult-to-machine ring does not come into contact with the mandrel, so it is not cooled by the mandrel, and a heated dummy ring is inserted, so the difficult-to-machine ring, especially Less cooling in corners. Therefore, in the hole expansion or hole expansion shaping of the difficult-to-machine ring, surface cracks do not occur at the corners or the like of the inner diameter surface. In the method for forging a difficult-to-work ring according to the present invention, when the dummy ring is made of a material having better hot workability than the difficult-to-work ring, it is necessary for forging compared to a material having poor hot workability. Pressure can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forging a difficult-to-machine ring according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram for explaining a forging method for a difficult-to-machine ring according to the present invention.
One example of the method of forging a difficult-to-work ring according to the present invention is to insert a dummy ring 2 made of a material having better hot workability than the difficult-to-work ring 1 into the inner surface of the difficult-to-work ring 1, and to form a dummy ring. After simultaneously heating the difficult-to-machine ring 2) into which the ring 1 is inserted, the core metal 3 is inserted. That is, the hole is placed on the metal core base 4 and forged with the anvil 5 to perform hole expansion or hole expansion shaping.

[0009] The difficult-to-machine ring in the method for forging a difficult-to-machine ring of the present invention includes duplex stainless steel, Ni super alloy, C
o A ring made of a difficult-to-work material such as superalloy or heat-resistant Fe-based steel. Since a dummy ring is inserted into the inner diameter surface of the difficult-to-machine ring, it is preferable that the inner diameter surface is cut by forging and then machined to form a cylindrical space.

[0010] The dummy ring used in the method of forging a difficult-to-work ring of the present invention may be made of the same material as the difficult-to-work ring, such as a material having poor hot workability. It is preferable to use a material of good quality because the pressure required for forging can be reduced. Also, since the dummy ring cannot be reused normally,
Inexpensive materials are preferred. As a material satisfying these conditions, carbon steel having C of 0.60% or less is suitable. Further, the thickness of the dummy ring is effective to some extent even if it is thin, but is preferably 50 mm or more.

In the method for forging a difficult-to-machine ring of the present invention, a dummy ring is inserted into the inner surface of the difficult-to-machine ring, and the heating can be performed by a usual method to a temperature for heating the difficult-to-machine ring. . The hole expansion or hole expansion shaping by forging can be performed in the same manner as in the case where the dummy ring is not used. In addition, in the forging method for a difficult-to-machine ring according to the present invention, hole expansion in forging or removal of the dummy ring after hole expansion shaping can be performed by mechanical cutting.

Hereinafter, embodiments of the present invention will be described.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A difficult-to-work ring 1 made of duplex stainless steel having an outer diameter of about 1000 mm, a thickness of 250 mm, and a height of about 250 mm has a diameter of 500 mm, a thickness of 100 mm, and a height of 2 mm.
Dummy ring 2 made of 50m JIS S45C steel
Was inserted. Both are heated to about 1200 ° C. and the diameter is 300
After forging until the surface temperature becomes about 900 ° C., the dummy ring is removed by machine cutting, the outer diameter is about 2000 mm, the wall thickness is about 100 mm, and the height is about 250 m.
m duplex stainless steel rings were produced. This duplex stainless steel ring was not cracked when visually observed. In addition, when the surface was cut by about 15 mm and the penetrant inspection was performed, no crack was found.

[0013]

According to the method for forging a difficult-to-machine ring of the present invention, by employing the above-described structure, the difficult-to-machine ring having poor hot workability such as a duplex stainless steel or a Ni super alloy is subjected to forging or hole-shaping by forging. It has an excellent effect that cracking does not occur even if it is performed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram for explaining a method of forging a difficult-to-machine ring according to the present invention.

FIG. 2 is an explanatory diagram for explaining a manufacturing process when a ring is manufactured by free forging.

FIG. 3 is a conceptual diagram for explaining a conventional method of expanding and shaping a ring by forging.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Difficult-to-process ring 2 Dummy ring 3 Metal core 4 Metal core base 5 Anvil 6 Ring to be processed

Claims (2)

[Claims] 1. A forging method for a difficult-to-machine ring, comprising inserting a dummy ring into the inner surface of the difficult-to-machine ring, heating the two at the same time, and then expanding or shaping the hole by forging. 2. The forging method for a difficult-to-work ring according to claim 1, wherein the dummy ring is made of a material having a higher hot workability than the difficult-to-work ring.