JPS58196136A - Manufacture of end plate unified with nozzle of pressure vessel - Google Patents

Abstract

PURPOSE:To form an end plate unified with a nozzle by forging a circular disk from a steel ingot, pressing in a tapered ring to form an annular groove, extending the outside of the groove to form a flat tabular blank, heating the blank and pressing to specified shape. CONSTITUTION:A steel ingot is formed successively to a circular disk by upset forging. A tapered ring 2 having inner diameter nearly equal to outer diameter of the nozzle of an end plate is put at the center, and pressed in applying downward force. Outer part of the annular groove 1a thus formed is forged and extended to form a blank 3. Next, the blank 3 is heated and placed on a lower die 4 and pressed by an upper die 5. At this time, a concavity 4a having curved face corresponding to the tank head to be formed is provided, and a relief 4b for the nozzle is provided at the center of the concavity 4a. The upper die 5 has a convex curved face corresponding to the end plate to be formed, and the diameter is made smaller than inner diameter of the end plate. Thus, contact area with the blank 3 is small, and no ironing is performed. Accordingly, forming is possible by small pressing force.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing a nozzle-integrated end plate for a pressure vessel.

Conventionally, a head plate with a nozzle for a large pressure vessel has been constructed by forming a hole in a substantially hemispherical head plate formed by hot-opening from a rolled material, and joining a nozzle thereto by welding.

However, the nozzle-equipped end plate manufactured by such a method has welded joints, so defects and deterioration of the welded joints have been a problem. For this reason, for example, in cases where particularly high safety is required, such as in the case of pressure vessels for nuclear reactors, it is necessary to regularly monitor welded parts even during operation, in order to eliminate the above problems. However, conventional press forming methods require extremely large capacity press equipment.
In reality, it was impossible.

The present invention has been made by focusing on the above-mentioned problems in the conventional manufacturing method of a nozzle-equipped end plate for a pressure vessel, and proposes a method for manufacturing a nozzle-integrated end plate without using a large-capacity press device. The purpose is to obtain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. 1 to 9 of the accompanying drawings showing embodiments thereof.

First, a steel ingot as shown in Fig. 1 is formed into a disc 1 by swaging forging as shown in Figs. 2 and 3, and then, as shown in Fig. Apply the tapered ring 2, apply downward force to the tapered ring 2, and press the fifth
Push it into the disc 1 as shown in the figure. The inner diameter of the tapered ring 2 is approximately equal to the outer diameter of the nozzle on the end plate.Next, when the tapered ring 2 is pulled out, an annular groove 1a is formed in the disk l as shown in FIG. Next, the outer part of the annular groove 1a of the disk 1 is forged and expanded to form a blank 3 having the shape shown in FIG. 7 (machining is performed if necessary). Next, the blank material 3 is heated to a temperature of 800 to 1300 DEG C., and as shown in FIG. 8, the blank material 3 is placed on a lower mold 4 and pressed by an upper mold 5. The lower mold 4 has a recess 4a having a curved surface corresponding to the curved outer wall of the mirror plate to be manufactured, and a recess 4b for the nozzle is provided in the center of the recess 4a. The upper mold 5 has a convex curved surface corresponding to the curved inner wall of the end plate to be molded, and its diameter is smaller than the inner diameter of the end plate to be molded. By pressing this upper mold 5 using a press device, the blank material 3 is pushed into the state shown in FIG. 9. With this, the 9th
A nozzle-integrated end plate 6 having a shape as shown in the figure is completed.

The upper mold 5 has a substantially partially spherical shape and its diameter is smaller than the inner diameter of the end plate, so the contact area between the upper mold 5 and the blank material 3 is small and there is no ironing process, so the pressing force is small. However, it can be easily molded.

As described above, according to the present invention, in a method for manufacturing a head plate of a pressure vessel having an integrally formed nozzle, a disk is forged from a steel ingot, and a taper having an inner diameter approximately corresponding to the diameter of the nozzle is formed. An annular groove is formed by pushing the ring into a predetermined position on the disc, and the outer part of the annular groove on the disc is forged and expanded until it has approximately the thickness of the head plate, thereby making the head plate into a flat plate. A blank material with an expanded shape is made, and this blank material is heated to the hot forming temperature and then formed into the specified shape by the upper and lower molds attached to the press equipment, so the powerful press equipment can be used. The nozzle-integrated mirror plate can be formed with a small pressing force without the need for As a result, it is possible to easily obtain a nozzle-equipped end plate without a welded portion, and various conventional problems associated with the presence of a welded portion can be solved.

The shape of the end plate can be formed by changing the shape of the blank material and the mold, even if the cross-sectional shape is arbitrary, such as a circle or an ellipse, and the shape of the mold is made to correspond to the shape of the end plate.

[Brief explanation of the drawing]

Figures 1 to 7 are diagrams showing the shape of the material at each stage of forging a steel ingot into a blank material, Figure 8 is a diagram showing the mold and blank material before forming, and Figure 9 is a diagram showing the finished material. It is a figure which shows the metal mold|die and blank material at the time of i completion. 1... Disk, 2... Taper ring, 3... Blank material, 4... Φ lower mold, 5 ψ... upper mold, 6... Φ mirror plate with nozzle. Patent Applicant Japan Steel Works Co., Ltd. Agent Patent Attorney Toshiyuki Miyauchi Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7r1! J

Claims (1)

[Claims] 1. In a method for manufacturing a head plate of a pressure vessel having an integrally formed nozzle, a disk is forged from a steel ingot, and a tapered ring having an inner diameter approximately corresponding to the diameter of the nozzle is formed into the disk. A circular groove is formed by pushing the disk into a predetermined position, and the outer part of the circular groove of one disk is forged and expanded until it becomes approximately the thickness of the head plate, so that the head plate is expanded into a flat plate. Manufacture of a nozzle-integrated head plate for a pressure vessel, which is characterized in that a blank material is prepared, and the blank material is heated to a hot forming temperature and then formed into a predetermined shape using an upper die and a lower die attached to a press device. Method. 2. The blank material is formed by the upper mold and the lower mold. The upper mold has a substantially partially spherical shape with a convex curved surface corresponding to the inner wall curved surface of the final shape of the mirror plate, and the concave material mold has a concave shape corresponding to the outer wall curved surface of the final shape of the mirror panel. A method for manufacturing a nozzle-integrated end plate for a pressure vessel according to claim 1, which is carried out using a lower mold having a curved surface and a relief portion for the nozzle.