JP3479416B2 - Flange-integrated head plate for pressure vessel, method of manufacturing the same, and blank material thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flange-integrated end plate of a pressure vessel, a method for manufacturing the same, and a blank thereof, and is used for a close head and a bottom head of a large pressure vessel.

[0002]

2. Description of the Related Art A steel pressure vessel has a closed head assembly (top dome, top torus, head) attached to both ends of an elongated cylindrical body in which several cylindrical members (shells) are connected and joined by means such as welding. It is provided with a flange) and a bottom assembly (bottom dome, bottom torus). For example, Japanese Patent Publication No. 56-26526, Japanese Patent Publication No. 57-50581, and Japanese Patent Publication No. 62-5698 disclose top dome (bottom dome). , Which is generally referred to as an end plate), has been proposed.

Each of these prior arts is a method of manufacturing a dome, and a torus and a flange are joined to the dome by welding. If the torus and the flange are welded to the dome in this way, the structure is not reliable and the manufacturing cost is high, and it is necessary to regularly inspect the welded part after installation.

For example, when particularly high safety is required as in the case of a steel pressure vessel for nuclear reactors, it was necessary to regularly monitor the welded portion even during operation. If the dome, the torus, and the flange can be integrally formed, it is advantageous because the welded portion is eliminated.
A flange-integrated dome (end plate) was manufactured using the press molding apparatus shown in FIG.

In FIG. 16, reference numeral 1 denotes a blank material obtained by forging a disk from a steel ingot and press-forming it. The maximum wall thickness of the flange portion (the flange corner portion which is the maximum in the normal direction from the inner peripheral curved surface is Since it becomes advantageous, the dome (end plate) integrated with the flange is formed by using the press forming apparatus shown in FIG.
Was produced. In FIG. 16, 1 is a blank material obtained by forging a disk from a steel ingot and press-molding it, and the maximum wall thickness of the flange portion (the distance from the inner peripheral curved surface to the maximum flange corner portion in the normal direction). It is a material with a plate thickness. Reference numeral 2 is a male die (punch) of the press machine, and 3 is a female die of the press machine.

[0006]

If the blank 1 shown in FIG. 16 is bent (press-formed) while being heated to the hot forming temperature, the following problems occur. The plate thickness of the blank material is too large, a huge pushing force is required for bending, and a pressing device with an extremely large capacity is required, which is practically impossible. ; Since the blank material has an excessively large plate thickness, the material yield with respect to the final product shape is extremely poor and the cutting time after pressing is excessive, which is not economical. A springback phenomenon occurs during bending. Even if the thickened portion 1A is formed on the circumferential portion of the blank material and press-molded, the flange corner portions are lacking in thickness and the intended flange-integrated end plate is not obtained. When manufacturing a flange-integrated end plate, heat treatment such as quenching and tempering ensures the prescribed mechanical properties. However, the flange part and end plate part have a thick flange part and a thin end plate part. Since the difference in wall thickness is large, there is a difference in cooling rate during water cooling and quenching, which is an obstacle to obtaining a uniform end plate.

Therefore, the present invention provides a method for manufacturing a flange-integrated end plate by modifying the shape of a blank material without using a large-capacity pressing device or a blank material having an excessively large plate thickness. This is the first purpose. In addition, the present invention utilizes the C amount segregation, that is, the C amount (carbon amount) between the flange and the disk (dome portion) is high in the flange and low in the disk, thereby achieving the whole. A second object is to provide a flange-integrated end plate and a blank material having uniform mechanical properties throughout.

[0008]

The present invention takes the following technical means in order to achieve the above-mentioned first object. That is, the manufacturing method of the present invention according to claim 1 has a concave portion surrounded by a flange over the entire circumference of the disk, and the tapered surface gradually increases in thickness from the disk center of the concave portion to the radial outer surface. An outer peripheral thickening portion is formed, a blank material having a shape connected to the flange through the outer peripheral thickening portion is formed, and when the blank material is mounted on a lower die or a die of a press device, the lower die or the die The outer peripheral wall thickness increasing portion is mounted in the opening, and then the upper die of the pressing device is pushed into the bottom surface of the recess to integrally form the dome portion and the flange portion at the hot forming temperature. Is.

Further, the blank material of the present invention according to claim 2 has a concave portion surrounded by a flange over the entire circumference of the disc, and the thickness is gradually increased from the disc center of the concave portion to the entire radially outward direction. It is characterized in that an outer peripheral thickened portion is formed by the tapered surface, and the outer peripheral thickened portion is connected to the flange via the outer peripheral thickened portion. In the blank material according to the second aspect, a tapered surface is formed on the bottom surface of the concave portion or on the surface opposite to the flange or on both surfaces, and the outer peripheral thickening portion can be provided (claim 3).

Further, in the manufacturing method of the present invention according to claim 4, at least one surface of the disk is a tapered surface whose thickness is gradually increased from the center of the disk over the entire surface in the radial direction, and is connected to the tapered surface. To make a blank material having a shape with a wedge-shaped cross-section thickening portion, when mounting the blank material to the lower mold or die of a press machine, the thickening portion is mounted in the opening of the lower mold or die, After that, the upper die of the pressing device is pushed into the disc to integrally form the dome portion and the flange portion at the hot forming temperature.

Further, in the blank material of the present invention according to claim 5, at least one surface of the disk is a tapered surface gradually thickened from the center of the disk over the entire surface in the radial direction, and is connected to the tapered surface. It is characterized in that it has a thickened portion having a wedge-shaped cross section on the outer circumference of the disc. In the blank material according to claim 5, one surface of the disk may be a flat surface and the other surface may be a tapered surface or both surfaces of the disk may be tapered surfaces to form a thickened portion having a wedge-shaped cross section on the outer circumference of the disk. (Claims 6 and 7).

Further, a flange-integrated end plate of the present invention according to claim 8 is a flange-integrated end plate of a pressure vessel in which a dome portion and a flange portion are integrally formed in order to achieve the above-mentioned second object. The C amount (carbon amount) between the dome portion and the flange portion is characterized in that the dome portion has a low C amount and the flange portion has a high C amount.
The blank material of the present invention according to claim 9 is a blank material having a concave portion surrounded by a flange or a thickened portion having a wedge-shaped cross section, and the C amount of the concave portion and the flange or the thickened portion is The concave portion has a low C content and the flange or the thickened portion has a high C content.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 (A) and (B) are claims 1
2A and 2B show the steps of the manufacturing method according to FIG.
(C) shows the blank according to claim 2, that is, the blank used in the manufacturing method according to claim 1.

2 (A) (B) (C), the blank 10 has a recess 12 surrounded by a flange 11 over the entire circumference of the disk, and the bottomed portion 12A of the recess 12 is a flat surface. The inner peripheral portion 12B of the flange has a draft angle, and a tapered surface 13 gradually increasing in thickness from the disk center 0 of the recess 12 over the entire radial direction is formed on the surface opposite to the flange 11. The tapered surface 13 is connected to the flange 11 via the outer peripheral thickened portion 14.

The blank 10 is made by cutting a cylindrical steel ingot and then axially compressing (forging) it to form a thick disk. Depending on the case, a thick disk is created by repeating compression and forging to perform sufficient forging. By press forming (free forging) this thick disk,
The above-mentioned blank material 10 shown in (A), (B), and (C) is created.

If the pressing force is sufficient, the recess 12 or the like can be formed by one push, but when it is difficult to make one push, the push is performed several times. It is desirable that the material that has been forged in this way be subjected to sufficient heat treatment so that it has the mechanical properties required for the finished product, that is, the end plate of the pressure vessel, at the time of material processing. The blank material 10 shown in FIGS. 2 (A), (B) and (C) is obtained by machining the entire surface or a part thereof according to
To create.

The blank 10 is heated to a hot forming temperature, for example, a temperature of 700 to 1200 ° C., and the blank 10 is heated as shown in FIG.
As shown in (B), it is attached to a die 16 of a press machine and pressed by pressing an upper die 15 shown by a hemispherical punch. When the blank material 10 is mounted on the die 16 of the press machine, the outer peripheral thickened portion 14 is inserted into the opening of the die 16 to attach the flange 11 to the die 16.
The disk center 0 is mounted with the center of the die as the center of the die, and then the upper die 15 of the pressing device is attached to the bottom surface 12 of the recess 12.
The dome portion and the flange portion are integrally molded at the hot molding temperature by pressing the dome portion into A.

Here, the bottomed surface 12A of the concave portion 12 is a portion corresponding to the dome portion 17A of the end plate 17 when this is pressed by the upper die 15 in the axial direction (vertical direction), and the thickened portion 14 is formed. Similarly, it is a portion corresponding to the torus portion 17B, the flange 11 is also a portion corresponding to the flange portion 17C, and the bottom surface (part) 12A of the recess 12 is a bulging process (bending forming) for reducing the thickness of each portion. , Its center 0
By forming a tapered surface 13 that is thin and gradually thickens over the entire surface in the radial direction, it becomes dead metal in contact with the upper die 15 and is expanded (expanded) around the periphery when bulging is performed. The increased-thickness portion 14 prevents breakage without causing wall thickness.

Further, since the upper die 15 has a substantially spherical shape and the diameter thereof is smaller than the inner diameter of the dome portion 17A, the contact area between the upper die 15 and the bottom surface 12A is small and the ironing is substantially performed. The arrow F1 in FIG.
As described above, since it is sufficient to uniformly extend in the normal direction, even if the pressing force amount F is small, sufficient molding is possible.

The blank material 10 shown in FIG. 2 is one in which the flange 11 is completely preformed. The size of the flange 11 is the flange 17C of the end plate 17 with a little extra thickness. Is desirable. Further, the bent end plate 17 is taken out from the press machine and subjected to necessary processes (for example, forming bolt insertion holes in the flange 17C) to become a complete product.

FIGS. 3A and 3B show an embodiment in which a female die (lower die) 16A having a die 16 is adopted as the forming means of the press machine, and the blank material 10 has the same shape as that of FIG. The common parts are denoted by common reference numerals, and the female mold 16A has a ring shape and is divided as shown in the drawing, and its mold surface 16B is a curved surface along the outer peripheral surface shape of the dome portion 17A.

FIGS. 4 (A) and 4 (B) show an embodiment for claim 4 and claim 5, in which the blank 10 has a different shape. That is, in the blank material 10, one surface of the disk is a flat surface 12A, and the other surface of the disk is a tapered surface 13 in which the thickness is gradually increased from the center of the disk to the entire radially outward direction.
And a recess 12 surrounded by the thickened portion 14 is formed on the side of the die 16 so as to be connected to the tapered surface 13 and has a thickened portion 14 having a wedge-shaped cross section on the outer circumference of the disc. Has been done.

That is, in the blank material 10 shown in FIGS. 4A and 4B, the thickened portion 14 having a wedge-shaped cross section is a portion corresponding to the torus 17B and the flange 17C of the end plate 17, and the shape thereof is a mold insert. The end surface of the product opening side after
There is a gradient by an angle θ such that the outer peripheral surface of the flange 17C is vertical θ1 at an angle θ of 5 to 20 ° with respect to the center of the outer peripheral radius (the center (dome center) on the axisymmetric center line and the opening end face position). The difference is the so-called cutback dimension).

The angle θ may change depending on the required final shape of the product and the like. This FIG. 4 (A) (B)
The blank material 10 shown in FIG. 2 is the blank material 1 shown in FIG.
Although the surplus material is slightly larger than 0, the material upsetting is shallow and the material yield is good. Thus, FIG.
As shown in (A), when the blank material 10 is mounted on the lower mold 16A or the die 16 of the pressing device, the lower mold 16A
Alternatively, the thickened portion 14 is inserted and installed in the opening of the die 16, and then the upper die 15 of the pressing device is pushed into the flat surface 12A of the disc to form the dome portion and the flange portion at the hot forming temperature. Is integrally molded.

In the above two embodiments, it is effective to use SA-508, class 2 or class 3, that is, manganese-molybdenum steel as the material of the blank material 10, especially in the case of a pressure vessel of a nuclear reactor. Is. Further, in each of the above embodiments, the press device is a vertical press, but it may be a horizontal press device, in which case the upper mold is a male mold and the lower mold is a female mold. There is no end.

Further, in the shape of the blank material, the disc means not only a perfect disc but also an ellipse or the like,
Further, although the end plate is not shown with a nozzle, it is of course possible to apply a nozzle with a nozzle.

[0027]

[Example] As a material, a typical reactor material is ASME section IISA508, class 3 (corresponding JIS, SFV
A thick ingot having an outer diameter of 5000 mm and a thickness of 1600 mm was prepared by forging from a steel ingot having a weight of 300 tons containing Q2A) as a component. From this thick disc 1200 to 800
Freely forged in the temperature range of ℃, press the punch for free forging into a concave part with an inner diameter of 3500 mm in the center, heat-treat it by launch annealing, quenching, tempering, etc.
A blank material 10 having a height of 1, 1500 mm, a depth of the recess 12 of 870 mm, and an inner diameter of the recess 12 of 4050 mm was prepared.

This blank material 10 was heated at 1200 ° C. to 110 ° C.
After heating in the hot forming temperature range of 0 ° C., it was attached to the lower die of the press machine and then indentation was performed by the upper die (indentation force 11,000 tons, indentation depth 1400 mm,
Pushing time is 20 minutes. The indented (bending) end plate did not have a wall thickness in the torus part, and the dome part and the flange part were integrally formed.

5 to 7 show another embodiment of the blank material 10 according to claim 1 or 2, and FIG. 5 shows that the bottom surface 12A of the recess 12 is gradually increased from the disk center O in the radial direction. The outer peripheral wall thickness increasing portion 14 is formed by the tapered tapered surface 13 and the tapered surface (bottomed surface) 13 and the anti-bottomed surface 12C is a blank material 10 which is a flat surface. According to the blank material 10 of FIG.
The material yield can be better than that of the blank material shown in FIG.

The blank material 10 of FIG. 6 has a bottom surface 12A and an anti-bottom surface 12C both formed on the tapered surface 13, and the directions of the taper are different, and the blank material of FIG. 7 is also used. 10 has both the bottomed surface 12A and the anti-bottomed surface 12C formed on the tapered surface 13, and the taper direction is the same, but the taper angle is different, and the tapered surface 13 is used in both FIGS. A peripheral thickened portion 14 is formed.

FIG. 8 shows a blank 1 according to claim 4 or 5.
0 is another embodiment, in which the tapered surface 13 is also formed on the side to be pushed in by the male shape (tool), and the other configurations are the same as those in FIG. 4 (A). According to the blank material 10 shown in FIGS. 5 to 8, the portion (surface) with which the tool 15 contacts
Since the taper surface 13 is radially outward from the center O of the disk, the tool 15 has a small misalignment and can be accurately pressed by the tool 15, that is, formed.

9 to 15 show an embodiment of claims 8 and 9, and FIGS. 9 (1) to 9 (8) show a large steel ingot 100.
The process of producing the blank material 10 by forging using is shown. The steel ingot 100 causes segregation with different component concentrations depending on the position, and carbon C is an element that is easily segregated. The top of the steel ingot 100 is high and the bottom is low. The larger the steel ingot 100, the greater the degree of segregation. On the other hand, carbon C is a quench hardening element, and the higher the amount of C, the higher the strength obtained.

In the hot forging of the blank material 10, the material of the contact surface of the tool is fixed by friction, and the fixed portion is wedged and pushed into the entire material.
In consideration of such a situation, a procedure for producing the blank material 10 will be described below with reference to FIGS. 9 (1) to 9 (8). Steel ingot 10
After rough forging 0, cut off the bottom unnecessary part 100A,
As shown in FIG. 9 (2), compression is applied in the axial direction, and thereafter,
Forging is performed again and sufficient forging is applied to the entire ingot (Fig. 9 (3)).
reference).

After that, after discarding the top unnecessary portion of the steel ingot 100 and the riser portion 100B (see FIG. 9 (4)), precompression and finish compression are performed again to form the outer peripheral curved surface of the disk and the outer periphery. I trained the club. That is, the pre-compression is performed by a wide tool that hits the entire compression surface, and the material of the contact surface of the tool is pressed into the entire material as a wedge to be retained on the bottom surface of the concave portion that becomes the end plate, while the final compression is 5 ~
The top is compressed by using a narrow tool having a contact surface of 25% and the material is moved in the plane direction so as to be positioned on the thick flange portion, after which the recess is formed using the punch 100C shown in FIG. 9 (7). .

The punch 100C is pushed in such a manner that the punch 100C is pushed at a position displaced from the center of the disc and is pushed sequentially in the circumferential direction and along the concentric circles to produce a blank material 10 as shown in FIG. 9 (8). . In the blank material 10 thus produced, as shown in FIG. 10, the carbon amount (C amount) of the disc bottom portion (recess) 10A and the inner peripheral portion 11A of the flange 11 is low when the bottom portion 10A is low. The peripheral portion 11A has a high C content, and the blank material 10 in which the C content segregation is taken into consideration is prepared by using the die or the lower die and the punch already described with reference to FIG. 1 or 2. Figure 13 is the end plate
As shown in, the material strength could be made uniform.

After the end plate portion was formed using the blank material 10 shown in FIG. 10, quenching and tempering were carried out. 12
13 shows the cooling curves of the respective parts A, B, C and D of the end plate shown in FIG.
, Each part A, B, from 880 ° C to 550 ° C
Table 1 shows the average cooling rates C and R of C and D.

[0037]

[Table 1]

Further, FIGS. 14 and 15 and Table 2 show the heating curves at the time of tempering of the respective parts A, B, C and D shown in FIG. 12 and the tempering parameter values showing the tempering effect, and the thick part ( (Flange) has a small rate of temperature rise, so the tempering effect will be small if tempered in the same time. Therefore, the flange strength was set to a high C content in order to achieve uniform material strength. There is.

[0039]

[Table 2]

As is clear from Table 2, the yield points (Y · S) of the B part and the D part have the same value, and it can be understood that the material strength can be made uniform by adding the C amount segregation. In addition,
In Table 2, T and S are tensile strengths, and _V E ₂₀ is an impact value. It is needless to say that each blank material shown in FIGS. 1 to 8 can be made into a more useful flange-integrated end plate by adding the C amount segregation shown with reference to FIG.

[0041]

As described above in detail, according to the present invention, the dome portion and the flange portion can be integrally formed, and the end plate having no welded portion can be formed with a small amount of force without the need for a powerful pressing device. Since the manufactured end plate has no welded portion, it has less structural defects and is useful as a end plate of a large-sized pressure vessel for which safety is particularly required.

Further, by adding the segregation of the amount of C, the mechanical properties can be made uniform and the safety can be further improved.

[Brief description of drawings]

FIG. 1 is a process drawing showing a first embodiment according to claim 1 of the present invention, (A) before pressing and (B) after pressing.

FIG. 2 shows a blank according to claim 2 of the present invention,
(A) is a cross-sectional view, (B) is a partial cross-sectional view of a plan perspective view, (C)
FIG. 4 is a partial cross-sectional view of a bottom perspective view.

FIG. 3 shows a second embodiment according to claim 1 of the present invention,
(A) is before pressing and (B) is after pressing.

FIG. 4 shows claim 3 of the present invention and a blank material thereof, (A) is a sectional view, and (B) is a partial sectional view of a bottom perspective view.

FIG. 5 is a cross-sectional view showing a second embodiment of a blank material.

FIG. 6 is a cross-sectional view showing a third embodiment of a blank material.

FIG. 7 is a cross-sectional view showing a fourth embodiment of a blank material.

FIG. 8 is a sectional view showing a fifth embodiment of a blank material.

FIG. 9 is a process drawing showing the procedure for producing a blank material.

FIG. 10 is a cross-sectional view of a blank material in which C content segregation is added.

FIG. 11 is a cross-sectional view of an end plate in which C content segregation is added.

FIG. 12 is a diagram in which positions are specified to show cooling of each part of the end plate shown in FIG. 11;

13 is a diagram showing a cooling curve of each part shown in FIG.

FIG. 14 is a diagram showing a heat treatment heating curve of each part shown in FIG. 12;

15 is a diagram showing tempering parameter values at respective positions shown in FIG.

FIG. 16 is a configuration diagram of a conventional example.

[Explanation of symbols]

10 blank material 11 flange 12 recess 13 Tapered surface 14 Thickening part 15 Upper mold 16 dice 16A lower mold

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masato Takeuchi Inventor 2-3-3 Niihama, Arai-cho, Takasago, Hyogo Prefecture Kobe Steel Works Takasago Works (72) Inventor Michio Kiguchi 2-chome, Niihama, Arai-cho, Takasago, Hyogo Prefecture No. 3-1 Kobe Steel Co., Ltd. Takasago Works (72) Inventor Eiichi Hisa, 2-33-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Kobe Steel Works Takasago Works (56) Reference: JP-A-58 -196135 (JP, A) JP-A-6-114479 (JP, A) JP-A-6-210363 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21D 51/24 B21D 22/20 B21K 21/02 B65D 88/06 F17C 13/00 301

Claims (9)

(57) [Claims] 1. A peripheral thickening portion is formed by a tapered surface having a concave portion surrounded by a flange over the entire circumference of the disc, and gradually thickening from the disc center of the concave portion over the entire surface in a radial direction. A blank material having a shape connected to the flange through an outer peripheral thickening portion is made, and when the blank material is attached to a lower die or a die of a press machine, the outer peripheral thickening portion is provided in an opening portion of the lower die or die. A method for manufacturing a flange-integrated type end plate of a pressure vessel, characterized in that the upper mold of the press device is pushed into the bottom surface of the recess to integrally mold the dome portion and the flange portion at a hot molding temperature. . 2. An outer peripheral thickened portion is formed by a tapered surface having a concave portion surrounded by a flange over the entire circumference of the disc, and gradually thickened from the disc center of the concave portion over the entire radial direction. A blank material for a flange-integrated type end plate of a pressure vessel, which has a shape connected to the flange through an outer peripheral thickened portion. 3. The blank of the flange-integrated end plate of a pressure vessel according to claim 2, wherein a tapered surface is formed on the bottom surface of the recess or on the surface opposite to or on both sides of the flange to provide an outer peripheral thickened portion. Material. 4. At least one surface of the disk is a tapered surface whose thickness is gradually increased from the center of the disk over the entire surface in the radial direction, and a shape having a thickened portion having a wedge-shaped cross section is connected to the tapered surface. When a blank material is made and the blank material is attached to the lower die or die of the pressing device, the thickened portion is attached in the opening of the lower die or die, and then the upper die of the pressing device is attached to the disc. A method for manufacturing a flange-integrated type end plate of a pressure vessel, characterized in that the dome portion and the flange portion are integrally molded at a hot molding temperature by pushing. 5. A thickened portion having a wedge-shaped cross-section is connected to the tapered surface so that at least one surface of the circular disk is gradually thickened from the center of the circular disk over the entire surface in the radial direction. A blank material for a flange-integrated end plate of a pressure vessel, which is characterized in that 6. The pressure according to claim 5, wherein one surface of the disk is a flat surface and the other surface is a tapered surface, and a thickened portion having a wedge-shaped cross section is provided on the outer circumference of the disk. Blank material for container end plate with integrated flange. 7. The both sides of the disk are tapered surfaces,
6. A flange-integrated end plate for a pressure vessel according to claim 5, a method of manufacturing the end plate, and a blank thereof, wherein a thickened portion having a wedge-shaped cross section is provided on the outer circumference of the disc. 8. A flange-integrated type end plate of a pressure vessel in which a dome portion and a flange portion are integrally formed, wherein the C amount (carbon amount) between the dome portion and the flange portion is low in the dome portion.
The flange integrated type end plate of the pressure vessel, wherein the flange portion has a high C content. 9. A blank material having a concave portion surrounded by a flange or a wedge-shaped cross-section thickening portion over the entire circumference of the disk, and the C amount of the concave portion and the flange or the thickening portion is a low C amount in the concave portion. A blank material for a flange-integrated type end plate of a pressure vessel, wherein the flange or the thickened portion has a high C content.