JP5180669B2 - Mouthpiece shell manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a squeezed shell of a large ring member for a pressure vessel having a cylindrical end portion squeezed in order to join hemispherical end plates.

  For large pressure vessels such as reactors for chemical equipment and pressure vessels for nuclear power, a mouthpiece provided at the end of a straight cylindrical shell (straight shell, hereinafter referred to as cylindrical shell or cylindrical shell portion) of the main body A hemispherical end plate is joined to the part. Conventionally, when the diameter of the hemispherical end plate and the outer diameter of the cylindrical shell of the main body portion are greatly different, as shown in FIG. 3A, a ring shape is formed between the hemispherical end plate 10 and the cylindrical shell 9d. The intermediate members called Dutchman 11 having different outer diameters at both end surfaces are joined together. However, in this joining method in which the intermediate member is interposed, the weld line is increased and the manufacturing cost is increased. Therefore, by forming the Dutchman 11 and the cylindrical shell 9d integrally, as shown in FIG. There has been a demand for a mouth shell having a mouth portion 9c formed therein.

  For example, in Patent Document 1, as shown in FIGS. 4 (a) and 4 (b), when forging while rotating a straight cylindrical forged member between a core metal 5b and an anvil 6b, the core A large ring ring forging method in which a step portion 5c is provided on the gold 5b and the end portion of the forged material 1d is lowered into the step portion 5c during forging of the forged material 1d. Is disclosed.

Further, in Patent Document 2, as shown in FIGS. 5A and 5B, mouth drawing is performed by causing a die 12 for die forming having a taper on the inner surface to act on the end of the forged ring member 1e. In this case, the forging ring member 1e is subjected to a thinning process or a notch process in the circumferential direction of the forging ring member 1e. A mouth-drawing molding method is disclosed in which a molding die 12 is acted by a press anvil 16 via a plate 15 for uniform reduction.
Japanese Patent Publication No.55-24378 JP 63-317231 A

  However, in the case of forming the squeezed portion by the forging method disclosed in Patent Document 1, the thinning due to the shrinkage occurs at the boundary between the squeezed portion 9c and the cylindrical shell portion 9d. In particular, in the case where the end portion of the cylindrical shell portion 9c is provided with a short protruding portion for supporting the container over the outer periphery thereof, it is necessary to increase the surplus in order to prevent the occurrence of the lack of thickness, which increases the cost. And forging process design becomes difficult. In the mouth-drawing method disclosed in Patent Document 2, the mouth-drawing portion is not formed by diameter forging of the cylindrical shell portion (main body portion), but is pressed using the mouth-drawing forming die 12. Therefore, a mouth-drawing forming die 12 that matches the forging ring of the product is required, and the manufacturing cost increases. Further, when the diameter of the cylindrical shell portion is increased, the press load is also increased, which may be larger than the pressing force and cannot be manufactured.

For this reason, the applicant of the present invention prevents the occurrence of thinning by suppressing the shrinkage at the boundary between the mouthpiece portion and the cylindrical shell portion, and the outer peripheral surface of the cylindrical shell portion 9d that may occur depending on forging conditions. In order to prevent the occurrence of taper and reduce the machining margin and improve the product yield, as shown in FIG. 6, the notch 7 is machined on the outer peripheral surface of the ring-shaped material 1f, and the machining position and diameter forging are processed. Disclosed a method for manufacturing a mouth-opening shell in which forging conditions such as the rolling reduction in the above are optimized (see Patent Document 3).
JP 2007-111700 A

  However, when the aperture shell is manufactured by the forging method disclosed in Patent Document 3 (see FIGS. 6A and 6B), the closing of the boundary between the aperture portion 9c and the cylindrical shell portion 9d is suppressed. Although it is possible to prevent the occurrence of the lack of wall and the taper of the outer peripheral surface of the cylindrical shell portion 9d, when the outer diameter D of the ring-shaped material 1f increases, the cylindrical shell by the diameter-enlarging forging As the diameter of the portion 9d is increased, the aperture diameter Da of the aperture restriction portion 9c is also increased, so that it is difficult to design a forging process such as setting the number of rotations and reduction ratio for the target aperture amount δa in the diameter expansion forging. There is a possibility that the aperture amount cannot be reduced to the target value.

  Accordingly, an object of the present invention is to manufacture a mouthpiece shell in which a notch is machined on the outer peripheral surface of a ring-shaped material, and a mouthpiece portion is formed integrally with the end portion of the cylindrical shell by diameter expansion forging. On the other hand, even for large-diameter ring-shaped materials, it is possible to simplify the forging process design and increase the amount of drawing by preventing the diameter of the mouth-drawing part from expanding due to the expansion of the cylindrical shell part. It is to provide a method for manufacturing a shell.

  In order to solve the above problems, the present invention employs the following configuration.

The manufacturing method of the mouth-opening shell according to claim 1 includes a step of machining a notch on the outer peripheral surface of the ring-shaped workpiece, and the ring-shaped workpiece is rotated between the core metal and the anvil. In the manufacturing method of the aperture shell, in which the aperture portion is integrally formed at the end portion of the cylindrical shell by expanding the diameter while forging, the outer diameter or the wall thickness of the cylindrical shell is previously set. After preforming the squeezed portion until a predetermined value set, a step of performing a diameter expansion forging is performed, and after the preforming, the squeezing portion is cooled and the diameter squeezed portion is cooled while performing the diameter expansion forging. Features.

  According to a second aspect of the present invention, there is provided a manufacturing method of the mouthpiece shell, wherein a tip portion of the mouthpiece portion for cooling is an end surface of the tip portion.

  According to a third aspect of the present invention, there is provided a method for producing an aperture shell, wherein the cooling is performed with water or air or a gas-liquid mixture of water and air.

  According to a fourth aspect of the present invention, there is provided a method of manufacturing the mouth-opening shell, wherein the cooling is performed at a position on the end surface immediately below the upper anvil, or in a circumferential direction including this position. It is characterized by the fact that it is carried out by the nozzles respectively arranged at the positions.

  In the method of manufacturing the mouth shell according to claim 5, the cooling is performed so that the difference between the outer surface temperature of the cylindrical shell and the outer surface temperature of the mouth restrictor is in the range of 100 ° C to 300 ° C. It is characterized by.

  According to the present invention, a notch is formed on the outer peripheral surface of the ring-shaped material, and the ring-shaped material is subjected to diameter forging while rotating between the core metal and the anvil, so that the end of the cylindrical shell portion is apertured. When manufacturing the mouthpiece shell in which the parts are integrally formed, after the mouthpiece portion is preformed in the first half of the above-mentioned diameter expansion forging, the diameter of the finished portion is expanded while cooling the part such as the end face of the mouthpiece portion. Since the forging is performed, the increase in deformation resistance due to the temperature drop of the mouthpiece portion increases the tip restraint force of the preformed mouthpiece portion, which is accompanied by the finish diameter expansion forging of the cylindrical shell portion. The diameter of the mouth restrictor is prevented from expanding. This facilitates forging process design, such as setting the number of laps for the target drawing amount and setting the reduction ratio, making it possible to increase the drawing amount itself, and forging a mouth-drawing shell with a simple process design and low machining costs. Finished products can be obtained and product yield is improved.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  1A to 1D show a manufacturing process of the mouthpiece shell of the embodiment. After cutting the segregated portion at the upper end and the bottom, the heated steel ingot 1 such as carbon steel or low alloy steel (Cr-Mo steel or the like) is upset by upper and lower molds 2 and 3 (Upsetting). After that, the punch 4 is pierced by the punch 4, and at that time, the segregation at the center of the steel ingot and the void defect are removed (FIG. 1 (a)). In the next step, the cored bar 5 is inserted into the pierced material 1a, and the material 1a is forged to the finished length by the cored bar 5 and the upper anvil 6 and the internal structure is improved. A cylindrical material 1b for diameter expansion forging is formed (FIG. 1B). The cylindrical material 1b is expanded to the intermediate finish outer diameter D while the wall thickness t0 is decreased to t by the core metal 5 and the upper anvil 6 in the next first diameter expansion forging process. The resulting ring-shaped workpiece 1c is obtained (FIG. 1c). After the end of the first diameter expansion forging step, the upper anvil 6 that can move up and down is retracted upward, and the core metal 5 is inserted from the end surface E on the mouth-drawing side of the ring-shaped workpiece 1c. A V-shaped notch 7 having a depth h is machined in the circumferential direction of the outer peripheral surface at the required distance L1, as shown in FIG. 1 (e). Then, in the second diameter expansion forging step, the cored bar 5 is moved in the axial direction so that the end surface 5a is located immediately below the notch 7, and the mouth drawing is started (FIG. 1 (d)). . As shown in FIGS. 2 (a) and 2 (b), at the start of the squeeze molding, as shown in FIGS. From the spray nozzles 8 arranged at a total of eight positions S1 to S8 at equal intervals of 45 ° in the circumferential direction, including the position S1, the cooling water is jetted to the tip end face Ea, and the tip of the mouth restrictor 9a Is forced water cooled. In the second diameter expansion forging step, the outer diameter Db of the cylindrical shell portion 9b and the outer diameter Da of the tip of the mouthpiece portion 9a are measured by a non-contact size measuring instrument, and the mouthpiece amount δ (= (Db− Da) / 2) is displayed in real time. A plurality of the notches 7 may be provided in the axial direction on the outer peripheral surface of the aperture stop portion 9a. Further, the shape of the notch is not necessarily limited to the V shape.

  The temperature Tf of the aperture portion 9a and the temperature Tc of the cylindrical shell portion 9b at the time of forced cooling are measured at the position of the outer surface at the center in the longitudinal direction. Then, when the outer diameter Db of the cylindrical shell portion 9b is expanded and forged to a predetermined finished outer diameter, the temperature Tc of the cylindrical shell portion 9b and the temperature of the mouth restrictor portion 9a are obtained in order to obtain the target throttle amount δa. The cooling water flow rate (spray flow rate) during forced water cooling is controlled so that the difference ΔT in Tf becomes a target temperature difference in the range of 100 to 300 ° C. Note that the cooling position of the end face Ea of the distal end portion is not necessarily limited to eight places at equal intervals in the circumferential direction, and includes, for example, S1 and the position S5 of the axial object as long as it includes at least the position S1 directly below the upper anvil 6. Only two locations may be cooled. Further, the cooling part is not necessarily limited to the tip end surface Ea, and for example, the outer peripheral surface of the mouth restrictor 9a may be cooled. The cooling medium may be a gas other than air, such as nitrogen gas, and other gases may be used for the gas-liquid mixing mist.

  Further, depending on the size of the target aperture amount, such as when the target aperture amount δa is relatively small, in the second diameter expansion forging step, first, the core metal 5 is positioned with its end surface 5a immediately below the notch 7. As described above, after the mouth-drawing is started by moving in the axial direction, the mouth-drawing portion 9a is preformed until the outer diameter D or the wall thickness t of the cylindrical shell portion 9b reaches a predetermined value. As described above, finishing diameter expansion forging can also be performed while forced water cooling is applied to the tip of the aperture portion 9a. In addition, based on the aperture amount δ displayed in real time, when the displayed aperture amount δ tends to exceed the target aperture amount δa, Cooling can also be stopped. In this way, from the ring-shaped workpiece 1c having the outer diameter D and the wall thickness t, in which the V-shaped notch 7 having the depth h is processed on the outer peripheral surface in the second diameter expansion forging step, the outer diameter The forged finished product of the aperture shell 9 in which the aperture portion 9a is integrally formed at the end of the cylindrical shell portion 9b having the thickness D1 and the thickness t1 is manufactured.

A cylindrical material 1b having an outer diameter of 2760 mm, a thickness of 650 mm, and a length of 2300 mm is formed from a steel ingot (weight: 70 tons) of low alloy steel (steel grade SCM420) by the steps shown in FIGS. 1 (a) and (b). In the process shown in FIG. 1 (c), diameter forging was performed until the wall thickness t became 450 mm. The outer diameter of the workpiece 1c at this time is about 3000 mm. At the time of this diameter expansion forging, a V-shaped notch 7 having a depth h = 150 mm in the circumferential direction is processed on the outer peripheral surface at a position of 800 mm from the end surface E of the workpiece 1c, and then, as shown in FIG. As shown, the core metal 5 was moved in the axial direction so that the end face 5a was located directly below the notch 7, and mouth-drawing molding was started. From the start of the mouth drawing, as shown schematically in FIG. 1 (d), the end surface E of the workpiece 1c is forcibly cooled under the four conditions shown in No. 1 to No. 4 in Table 1, respectively. Then, the diameter forging was performed to the finished outer diameter (Examples 1 to 4). As a comparative example (No. 5), diameter forging was performed to the finished outer diameter without forced cooling. Table 1 shows the difference between the temperature Tc of the cylindrical shell portion 9b and the temperature Tf of the mouth throttle portion 9a under each condition, and the actual throttle amount (actual value) δm with respect to the target throttle amount (target value) δa. . In the case of spray water cooling, the nozzle (discharge) pressure is 3 kg / cm ² , the flow rate is 0.2 m ³ / h, and in the case of forced air cooling, the air flow rate is 4.8 Nm ³ / h.

  From Table 1, in either case of spray water cooling or forced air cooling, the mouth drawing is performed by the diameter expansion forging while cooling the tip end face of the mouth drawing without cooling. The aperture amount δ (actual value) can be made larger than the case (80% or more of the target value). In the case of spray water cooling, if the number of cooling locations in the circumferential direction is increased, the amount of restriction δ (actual result) also increases, and two locations, No. 4 position S1 directly below the upper metal pad + shaft target position S5 (see FIG. 2). When cooled, the aperture amount δ (actual value) is 105 mm, and an aperture amount of 95% or more with respect to the target value (110 mm) can be realized. Further, in the case of cooling eight locations at equal intervals in the circumferential direction of No. 1, a large aperture amount exceeding the target value (110 mm) can be taken. In this case, the target throttle amount can be realized by adjusting the cooling water flow rate or reducing the number of cooling points during the diameter expansion forging.

  The difference ΔT between the temperature Tc of the cylindrical shell portion 9b and the temperature Tf of the mouth throttle portion 9a is the case of cooling at one position S1 (see FIG. 2) immediately below the upper anvil, in either case of spray water cooling or forced air cooling. However, it is over 100 ℃ (No.2, No.3). Further, when cooling at eight locations at equal intervals in the circumferential direction, the temperature difference ΔT is 250 ° C. or more (No. 1). On the other hand, when cooling is not performed, the temperature difference ΔT is as small as 58 ° C., the throttle amount δ (actual value) is 85 mm, and remains below 80% of the target value (110 mm) (No. 5). Thus, when the temperature difference ΔT is a small value that does not reach 100 ° C., the throttle amount δ (actual value) cannot be too large. Further, when the temperature difference ΔT exceeds 300 ° C., the temperature of the mouth-drawn portion is lowered and the deformation resistance is remarkably increased, so that the end restraining force becomes too strong, the drawing amount δ becomes too large, and the diameter forging is increased. In the process, it becomes difficult to control the target throttle amount. Moreover, the variation in the circumferential direction also increases due to local cooling. Therefore, it is desirable to cool the tip of the mouthpiece portion so that the difference ΔT between the temperature Tc of the cylindrical shell portion 9b and the temperature Tf of the mouthpiece portion 9a is in the range of 100 ° C to 300 ° C.

It is explanatory drawing which shows typically the manufacturing process of (a)-(d) mouth-opening shell. (E) It is explanatory drawing which shows the notch processed into the outer peripheral surface of a ring-shaped workpiece. (A) It is explanatory drawing which shows typically cooling of the aperture | diaphragm | squeeze part front end surface in a diameter expansion forge process. (B) It is explanatory drawing which shows typically arrangement | positioning of the spray nozzle used for cooling. (A) It is explanatory drawing which showed typically the structure which joins a hemispherical end plate and a cylindrical main-body part using an intermediate member. (B) It is explanatory drawing which shows the integrated aperture diaphragm shell which provided the aperture diaphragm part in the edge part of a cylindrical main-body part. (A), (b) It is explanatory drawing which shows the method of manufacturing a caliber shell by the diameter expansion forging of a prior art. It is explanatory drawing which shows the method of manufacturing a mouth-opening shell by the press molding of a prior art. (A) It is explanatory drawing which shows the state which set the raw material between the metal core and anvil at the time of diameter expansion forging. (B) It is explanatory drawing which shows the state in which the aperture part was formed by diameter expansion forging.

Explanation of symbols

1: Steel ingot 1a: Material b 1b: Cylindrical material 1c: Ring-shaped workpiece 2, 3: Die 4: Punch 5: Core 5a: Core metal end face 6: Upper metal 7: Notch 8: Spray nozzle 9: Mouth restrictor shell 9a: Mouth restrictor 9b: Cylindrical shell E: Material end face Ea: Mouth restrictor end face

Claims (5)

It has a step of machining a notch on the outer peripheral surface of the ring-shaped workpiece, and the ring-shaped workpiece is subjected to diameter forging while rotating between the core metal and the anvil to thereby end the cylindrical shell. A method for manufacturing an aperture shell in which an aperture portion is formed integrally with a portion, wherein the aperture portion is reserved until the outer diameter or thickness of the cylindrical shell reaches a predetermined value. A method of producing a mouth shell , comprising a step of performing diameter expansion forging after forming, and performing diameter expansion forging while cooling the mouth portion after the preliminary molding .   The manufacturing method of the mouth-opening shell according to claim 1, wherein a tip end portion of the mouth-stopper portion that performs cooling is an end face of the tip end portion.   The method for producing a mouth shell according to claim 1 or 2, wherein the cooling is performed with water or air, or a gas-liquid mixture of water and air.   The cooling is performed by nozzles arranged at positions of the end face of the tip immediately below the upper anvil, or at a plurality of positions in the circumferential direction including this position, facing the end face of the tip. The manufacturing method of the mouth-opening shell of Claim 3.   5. The cooling according to claim 1, wherein the cooling is performed so that a difference between an outer surface temperature of the cylindrical shell and an outer surface temperature of the mouthpiece portion is in a range of 100 ° C. to 300 ° C. 5. The manufacturing method of the mouth-drawing shell of description.

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