JPH06238387A - Forging of long size steel - Google Patents

Abstract

PURPOSE:To enable forging of a long size steel having a high toughness and high strength shaft part by reheating to lower than the recrystallization temp. and forging a shaft part after upsetting one end upset part of bar stock having one end upsetting part capable of specifying a ratio of length diameter and a shaft part. CONSTITUTION:A bar stock 10 consisting of one end upsetting part 10 having 1-3 ratio of length/outside diameter and a shaft part 10 is flat upset with rotating a lower die 12 by press machine, forming to die shape. At this time, an upsetting ratio for forming fiber flow is made to >=1/2. Successively, changing an upper die to a punch, the upset part 10a is pressed in the die, obtaining a near net shape close to product's flange shape. Subsequently, before entering into forging stage, the bar stock 10 with flange part formed is reheated to the recrystallization temp. And the shaft part 10b of the bar stock 10 is forged at a forging ratio of >=2s by four face forging machine, improving a steel structure through refining of crystalline grain. By this forging stage, the shaft part is forged over 2000mm.

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 long steel material suitably applied to the manufacture of a long shaft of a large-sized aircraft engine having a flange portion integrally formed at one end.

[0002]

2. Description of the Related Art A large fan jet engine for an aircraft uses a long shaft forging material having a flange to which a fan disk is attached at one end (an umbrella portion 9 is integrally formed. As the material, for example, maraging steel is used, and in order to obtain necessary material mechanical properties such as improvement of material yield and toughness and tensile strength, the shaft part is stretched at a predetermined wrench ratio while The flange part is integrally formed by setting up the parts to obtain a shaft material with a shape (near net shape) close to the product shape.The conventional manufacturing method of this kind of shaft material is as follows: After forging the shaft portion, the flange is formed by upsetting the end portion with a pressing machine.

[0003]

However, as the engine becomes larger, there has been a demand for a long shaft forging material having a total length of 3000 mm. Since such a shaft material has a long shaft portion, it is almost impossible to set the end portion of the forged and stretched shaft in a press machine while standing upright. .

Therefore, when a steel material having the same outer diameter as the flange (umbrella) to be formed at the end is prepared, and the flange is left to be forged to a desired diameter and then the flange is formed by machining, the flange is formed. The fiber flow of the portion does not match the direction of the centrifugal force acting on the flange portion, and the strength requirement is not satisfied. The present invention has been made in view of such circumstances, in the shaft portion to improve the steel structure by refining the crystal grains by forging, has a required fiber flow in the flange portion, and, It is an object of the present invention to provide a method for forging a long steel material having a high toughness and high strength and having a shaft portion length of 2000 mm or more by achieving a net shape.

[0005]

In order to achieve the above-mentioned object, in the present invention, one end upsetting portion and shaft portion having a ratio L1 / D of the length L1 to the outer diameter D of 1 to 3 are provided. After setting up the one end upsetting part of the bar material having and with the upsetting ratio of 1/2 u or more, it is reheated to a recrystallization temperature or lower, and the shaft part is forged to a forging ratio of 2 s or more, and forged. The shaft length L2 is 2000
There is provided a method for forging a long steel material, which is characterized in that it is not less than mm.

In the method for forging a long steel material according to the present invention, the product shaft portion length L2 is 2000 m in which one end is integrally formed with an umbrella-shaped flange, a disk-shaped gear, a counterweight and the like.
m or more, for example, it is suitably applied to the manufacture of stub shafts for aircraft engines. 1 to 5 show steps of manufacturing a stub shaft of an aircraft engine according to the method of the present invention, and the details of the method of the present invention will be described with reference to these drawings.

First, a material (billet) 10 having a predetermined shape is prepared and set on the lower die 12 of the press. The steel type of the material 10 is not particularly limited as long as the steel structure can be improved by forging, but maraging steel or the like can be suitably applied. The material 10 has a round bar shape having a required outer diameter (D) and length, and is heated to a predetermined temperature. At the center of the upper surface of the lower die 12, a mold 12a for molding a flange portion of the product is formed. The material 10 has an upper end 10a protruding upward from the mold bottom of the mold 12a by a length L1, and the protruding portion 10a (length L1 × outer diameter D) serves as an upsetting portion. The ratio of the length L1 of the upsetting portion 10a to the outer diameter D (L1 /
D) is set to 1-3. The shape ratio (L
If 1 / D) is larger than 3, buckling may occur at the time of upsetting, and if it is smaller than 1, the fiber flow of the flange portion formed by upsetting is not formed in a required pattern.

The raw material 10 is flatly set up while the lower die 12 is rotated by a press machine, and put in a mold (FIG. 2).
The upsetting ratio at this time is preferably set to 1/2 u or more (in the entire specification, the expression "the upsetting ratio is set to 1/2 u or more" means that the upsetting ratio is 1 / 2u. , 1 / 2.5u, 1 / 3u, etc., which means that the installation amount is larger than the installation ratio of 1/2 u). In the case of less than this, the required fiber flow is not formed. . Then, the upper die is replaced with the punch 14, and the upsetting portion 10a is pushed into the mold 12a (FIG. 3), and a near net shape close to the flange shape of the product is obtained. Depending on the product, the in-mold pushing step using the punch can be omitted.

Next, in the forging step of the shaft portion 10b, before the forging, the material 10 having the flange portion formed is cooled to a temperature not higher than the recrystallization temperature (for example, 1100 in the above-mentioned maraging steel).
Reheat to below (° C). Then, the shaft portion 10b of the shaft material 10 is forged by a four-sided forging machine at a forging ratio of 1.5 s or more (FIG. 4). Although the detailed structure of the four-sided forging machine is not shown, this forging machine grips the material to be forged by the manipulator device, and uses four anvils 16 from four directions orthogonal to the axial direction of the material to be forged. It is a device for simultaneously pressing and forging (for example, reducing the diameter and tapering) the material to be forged by swaging, and this device is known. As the anvil 16, one having a shape that conforms to the flange shoulder shape of the end is used. If the forging ratio during forging is less than 1.5 s, the improvement of the structure (fine graining) cannot be obtained. The preferred training ratio is 2 s or more.
By this forging step, the forged portion, that is, the shaft portion 10b is 20
It is stretched to a length L2 of 00 mm or more (Fig. 5). In addition,
The forged shaft material 10 is then subjected to necessary heat treatment and machining.

[0010]

EXAMPLES The manufacturing method of the present invention was applied to the manufacturing of stub shafts for large aircraft engines. First, the outer diameter (D) 3
Billet 10 with a round bar shape of 50 mm x length 1600 mm
Is prepared and set on the lower die 12 of the press.
The billet 10 is the above-mentioned maraging steel and is heated to a predetermined temperature (for example, 970 ° C.). Lower die 1
A mold 12a for molding a flange portion of the product is formed at the center of the upper surface of the bill 2, and the billet 10 has an upper end 10a extending upward from the mold bottom of the mold 12a by a length (L1) 530.
It is set by protruding only mm, and this protruding part,
That is, the ratio of the length L1 of the upsetting portion 10a to the outer diameter D (L1 /
D) is 1.5.

The billet 10 is formed by pressing the lower die 1 with a press machine.
It was flatly set up while rotating 2 and was set in a mold (Fig. 2). Then, the upper die is replaced with the punch 14, and the upsetting unit 10 is replaced.
a was completely pushed into the mold 12a (FIG. 3), and a near net shape close to the flange shape of the product was obtained. Next, the material 10 in which the flange portion is molded is at a recrystallization temperature or lower 1
Reheat to 100 ° C, and shaft material 1 with a four-sided forging machine
0 shaft part 10b with a training ratio of 3s, length (L2) 3000
mm and shaft diameter (D2) 200 mm (FIGS. 4 and 5). As a result of observing the metal structure of the obtained shaft material 10 with a microscope, the average crystal grain size was # 8.3.

FIG. 6 schematically shows a change in fiber flow in the flange portion (umbrella portion) 10a of the shaft material 10 manufactured by the method of the present invention, and FIG.
6B shows a flow of the raw material 10 shown in FIG.
FIG. 6C shows the flow after the flat installation shown in FIG. 2, and FIG. 6C shows the flow after the punch shown in FIG. On the other hand, in FIG.
The fiber flow of the flange part when a shaft material is manufactured by the comparison method is schematically shown. In this comparison method, as shown in FIG. 7 (A), a billet having a size corresponding to the outer diameter of the flange portion at the time of production is prepared, and after the flange portion to be formed at this end is forged and stretched, The required flange is formed by machining (cutting). The broken line in FIG. 7B shows the outer shape of the flange formed by machining. The fiber flow of the shaft material 10 according to the method of the present invention extends along the radial direction, and according to the method of the present invention, the fiber flow of the flange portion on which the centrifugal force acts is compared with the flow of the comparison method, It can be formed into a preferable pattern.

[0013]

As is apparent from the above description, according to the method for forging a long steel material of the present invention, upsetting of the upsetting portion is performed before the shaft portion is forged. In addition, even when the length of the shaft portion of the product is 2000 mm or more, upsetting can be performed by the upsetting machine (press machine). Then, one end swaged portion having a ratio L1 / D of the length L1 and the outer diameter D of 1 to 3 is
Since it is set up to 2 u or more, a preferable fiber flow can be formed at the one end set-up portion thus set up. On the other hand, since the shaft portion is forged and stretched at a wrought ratio of 1.5 s or more, the crystal grains in this portion are refined, and it is possible to obtain a long steel material having a required material mechanical performance, that is, excellent toughness and high strength. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a method for forging a long steel material according to the present invention, in which a raw material is set in a die.

FIG. 2 is a cross-sectional view showing a state in which one end of a raw material is flatly set up by the manufacturing method of the present invention.

FIG. 3 is a cross-sectional view showing a state in which, after the flat upsetting process shown in FIG. 2, the punching process is performed into the mold.

FIG. 4 is a side view showing a state in which a material shaft portion is forged by the manufacturing method of the present invention.

FIG. 5 is a side view showing a state in which the forging process of the material by the manufacturing method of the present invention is finished.

FIG. 6 is a diagram showing a process of forming a fiber flow at an upset portion of a steel material manufactured by the manufacturing method of the present invention.

FIG. 7 is a diagram showing a process of forming a fiber flow at one end of a steel material manufactured by a comparative method.

[Explanation of symbols]

 10 Material (billet) 10a One end upsetting part 12 Lower die 12a type 14 Punch 16 Anvil

Claims (1)

[Claims] 1. The ratio L1 / D of the length L1 and the outer diameter D is 1 to 3.
After setting up the one end upsetting part of the bar material having one end upsetting part and the shaft part to an upsetting ratio of 1/2 u or more, it is reheated to a temperature lower than the recrystallization temperature, and the shaft part is forged to a training ratio. A forging method for a long steel material, which is forged for 2 seconds or more, and a length L2 of the forged shaft portion is 2000 mm or more.