JP6521369B2 - Hot forging die - Google Patents

Hot forging die Download PDF

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JP6521369B2
JP6521369B2 JP2015096235A JP2015096235A JP6521369B2 JP 6521369 B2 JP6521369 B2 JP 6521369B2 JP 2015096235 A JP2015096235 A JP 2015096235A JP 2015096235 A JP2015096235 A JP 2015096235A JP 6521369 B2 JP6521369 B2 JP 6521369B2
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mold
die
hot forging
corner
mold piece
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JP2016209908A (en
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昇平 佐々木
昇平 佐々木
松本 英樹
英樹 松本
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日立金属株式会社
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  The present invention relates to a hot forging die integrally formed by combining a plurality of die pieces.
In recent years, due to the demand for higher efficiency of steam turbines, turbine blades used in steam turbines have also been elongated. In the case of producing a long blade material exceeding about 1500 mm, the method of sandwiching the material between the upper mold and the lower mold and forming it into a blade material by large-size press forging is the mainstream. For example, Japanese Patent Laid-Open No. 4-46651 (Patent Document 1) twists a three-dimensional shape formed by mutually matching the striking surfaces of an upper mold and a lower mold having a three-dimensionally shaped die-cut surface. The invention of a method of manufacturing a turbine blade forging using the above cavity is disclosed. The upper mold and the lower mold disclosed herein are integrally formed of one metal material (see, for example, FIGS. 2 and 4 of Patent Document 1).
On the other hand, there is a proposal of Japanese Patent Application Laid-Open No. 2014-208379 (patent document 2) proposed by the applicant of the present application as a hot forging die suitable for a large size turbine blade.
Unexamined-Japanese-Patent No. 4-46651 JP, 2014-208379, A
Among the above-mentioned patent documents, the invention of patent document 2 makes it easy to form an arbitrary buildup layer in a desired portion of a large-sized hot forging die which is difficult to solve by patent document 1. It can be done. In addition, when a non-repairable defect such as a crack is generated in a part of the integrally formed hot forging die by using the divisible hot forging die, the hot forging die A part of the mold can be replaced, which is excellent as a hot forging die for obtaining a large forging.
As described above, in Patent Document 2, when a defect such as a crack occurs, it is easy to replace the mold piece in that part, but if it is possible to more reliably prevent the occurrence of the crack itself, a large turbine It can be made more suitable as a hot forging die for blades.
An object of the present invention is to provide a hot forging die capable of more reliably preventing cracking of a hot forging die used for manufacturing a large-sized forged blade for a turbine blade. It is to be.
Based on the invention disclosed in the above-mentioned Patent Document 2, the inventor examined various mold shapes in order to obtain a hot forging mold more suitable for obtaining a forging material for a large size turbine blade. As a result, it was found that by dividing the mold piece in the direction of the thrust load applied to the hot forging die at the time of hot forging, it is possible to reduce the stress applied to the entire hot forging die. The present invention has been reached.
That is, according to the present invention, there is provided a mold for hot forging for a turbine blade, in which an assembly of mold pieces integrally formed by joining a plurality of mold pieces is mounted as a core mold in a base mold. The hot forging die is provided with a die-cut surface in the form of the turbine blade, the die-cut surface is constituted by the plurality of die pieces, and the die-cut surface is in the longitudinal direction in the die-cutting face It is a mold for hot forging in which the plurality of mold pieces are joined so as to be divided obliquely with respect to each other.
Preferably, at least one of the mold piece and the base mold is a hot forging mold in which a working surface side is coated with a Ni-based super heat-resistant alloy layer.
The use of hot forging die of the present invention, for example in the production of turbine blades long, be more reliably possible to prevent problems such as cracks in the hot forging die, hot forging The lifetime of the forging die can also be improved.
It is a schematic diagram which shows an example of the assembly of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram which shows another example of the assembly body of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram which shows another example of the assembly body of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram which shows another example of the assembly body of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram which shows another example of the assembly body of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram which shows another example of the assembly body of the mold piece used for the metal mold | die for hot forgings of this invention. It is a schematic diagram of a hot forging die showing an example of the present invention. Is a schematic view seen from the engraved side of the hot forging die showing an example of the present invention. It is a cross-sectional schematic view of a peripheral gap of the hot forging die of the present invention. It is a diagram of simulation results showing the distribution of tensile applied to hot forging die stresses.
The present invention will be described using the drawings. However, the present invention is not limited by the embodiments described below. The term "hot forging" as used in the present invention also includes press forging and hot die forging in hot and constant temperature.
1 to 6 are schematic views showing an example of an assembly of a mold piece used for the hot forging mold according to the present invention, and FIG. 7 is an assembly of the mold piece in the base mold 3. It is a schematic diagram which shows an example of the metal mold | die for hot forgings provided with the body. The working surface of the hot forging die 1 is provided with a die-cut surface 4 in the form of a turbine blade.
The hot forging die 1 for a turbine blade of the present invention is mounted as an insert die in the base die 3 as an assembly of die pieces integrally formed by joining a plurality of die pieces 2. Be done. The hot forging die 1 is provided with a engraved surface 4 in the form of a turbine blade. The hot forging die 1 shown in FIG. 1 is used for the lower die. In order to obtain a desired turbine blade material shape by hot forging, the upper die having a die-cut surface is pressed by the lower mold and the upper die to form a turbine blade material shape.
In the present invention, the die-cutting surface is constituted by an assembly of a plurality of mold pieces, and the plurality of mold pieces are divided obliquely to the longitudinal direction in the die-cutting surface. Are joined. In the present invention, the “longitudinal direction in the mold engraving surface” means the direction shown by a broken line in FIG. 8 when the mold engraving surface 4 of the hot forging die 1 is viewed from above, the longitudinal direction of the material for turbine blades Same direction. And A line shown in FIG. 8 has shown an example of the parting line of a mold piece. The parting line of this mold piece is oblique to the longitudinal direction in the die-cutting surface. In the present invention, "diagonally with respect to the longitudinal direction" refers to division with a relationship other than a virtual dividing line (line B) orthogonal to the longitudinal direction in the mold engraving surface.
By the way, the material for a turbine blade formed by hot forging has a shape which is gradually twisted from the root direction toward the wing direction. Therefore, a thrust load is applied to the hot forging die formed into the material for a turbine blade along the twisted shape during hot forging. Therefore, the stress applied to each mold piece can be reduced by providing the mold pieces so as to divide in the direction of the large thrust load in the direction in which the thrust load is applied.
In the present invention, as described above, the mold pieces divided in the direction in which the large thrust load is applied are provided. Since the turbine blade material has a complicated shape, for example, it may be divided in a direction having an inclination of θ1 or may be divided in a direction having an inclination of θ2. The dividing angle (θ1 or θ2 in FIG. 8) is preferably an angle of approximately 20 to 60 °, and the dividing direction and the angle may be determined by performing simulation or the like, for example.
In the assembly of the mold piece 2 shown in FIG. 1, the die-cut surface 4 is divided at an angle of approximately 20 to 60 degrees. According to this shape, it is possible to relieve the stress due to the thrust load and to prevent the breakage of the hot forging die. The assembly of the mold piece 2 shown in FIG. 2 is further divided obliquely with respect to the height direction of the mold piece 2. With this structure, the contact pressure at the time of hot forging can be reduced by increasing the contact area between the mold pieces 2. Therefore, it is advantageous as a hot forging die with a large forging load. The assembly of the mold piece 2 shown in FIG. 3 is obtained by dividing the mold piece 2 into three or more pieces in accordance with the direction and the position to which the thrust load is applied. If large thrust and load are applied at a plurality of positions, the mold piece 2 can be divided into three or more pieces. Moreover, since division | segmentation to three or more will reduce the magnitude | size of one mold piece, it becomes possible to perform overlay welding easily with respect to the striking surface of the metal mold | die for hot forgings. As shown in FIG. 4, a stepped portion 15 may be provided in the middle of the divided surface in the height direction of the mold piece 2. When the step portion is provided, the stress concentration on the corner portion 14 can be prevented by providing the void portion 12 on both sides. In the present invention, as shown in FIG. 5 and FIG. 6, the mold piece 2 does not necessarily have to be divided from the striking surface side to the bottom side, and when the corner 13 and the corner 14 are formed It is desirable to provide 12 simultaneously to relieve stress concentration in the corners 14.
By mounting the assembly of the mold pieces shown in FIGS. 1 to 6 described above in the base mold 3 shown in FIG. 7 as an insert mold, the mold 1 for hot forging can be obtained. .
Further, in the present invention, when the stepped portion is provided in the height direction of the mold piece, as shown in FIG. 9, the chamfered portion 11 is formed at the tip of the corner portion 13 of the mold piece 2 The void 12 may be provided in a part of the place where the contact is made. By providing this void portion 12, it is possible to further alleviate the stress applied to the mold piece. In particular, in the case of manufacturing a large forged product by hot forging having a maximum load of 10,000 tons or more, the combination of the corner 13 and the corner 14 having no void 12 has a corner. The mold piece 2 on the side may be broken. Therefore, in the present invention, in order to prevent the mold piece 2 from being broken, it is preferable to provide the void 12 to reduce the stress applied to the mold piece 2.
When a specific representative example is shown, as shown in FIG. 9, a first mold piece (mold piece A) having a corner 13 and a second metal having a corner 14 corresponding to the corner 13 In the joint portion with the mold piece (mold piece B), the gap portion 12 constituted by the chamfered portion 11 is provided. In addition, the "corner part" said by this invention is a convex corner part, and it chamfers and a chamfer is formed. Also, as shown in FIG. 9, “corner” refers to a concave portion (corner 14) to which the corner 13 having the chamfered portion 11 is fitted.
The chamfered portion may be flat or curved. Of course, a combination of a flat surface and a curved surface may be used. Further, the shape of the corner portion 14 of the second mold piece (mold piece B) may also be flat, curved or a combination thereof. The particularly preferable shape of the corner portion 14 is a curved shape. This is because the curved surface can reduce the stress applied to the corner portion 14 of the second mold piece (mold piece B) at the time of hot forging.
According to the study of the present inventor, if the radius of the curved surface of the corner 14 is 10 mm or more, the fracture of the second mold piece (mold piece B) is performed even when hot forging of several tens of thousands of tons is performed. The effect of suppressing Further, in this case, it is preferable that the shape of the chamfered portion 11 also be a curved surface and be larger than the radius of the curved surface of the corner portion 14.
In addition, the space | gap part 12 of this invention exceeds the dimensional difference at the time of fitting mold piece 2 comrades. For example, L and M shown in FIG. 9 are the height direction L of the gap and the length in the width direction M, and the height L of the gap is approximately 10 to 60 mm and the width M is approximately 10 to 60 mm It is good to assume. The height and width of the gap 12 formed by the chamfered portion 11 and the corner portion 14 are the effect of reducing the stress applied to the periphery of the corner portion 14 during hot forging, and the first mold piece (mold piece A) It may be determined in consideration of the clamping force with the second mold piece (mold piece B). In the case of forming a radius at a corner, the height and the width of the void are defined as the contact points of the straight portion and the radius.
Moreover, it is preferable that the radius of the radius of the corner part 14 is 15 mm or more. This is because the effect of reducing the tensile stress applied around the corner is large. Preferably it is 16 mm-26 mm. At this time, chamfering of the corner corresponding to the corner is chamfered not less than the radius of curvature of the corner.
Here, the result of simulating the change of the tensile stress is shown based on the relationship with the void portion formed by the chamfered portion. The simulation software used is based on the commercially available finite element method. In addition, the shape of the chamfered portion and the shape of the corner formed on the first mold piece and the second mold piece is the shape shown in FIG. 10, and the relationship between the maximum tensile stress generated at the corner and the corner radius is It shows in Table 1 and FIG.
In the structure in which the void portion was not formed, the maximum tensile stress generated at the corner exceeded 1500 MPa, whereas in the shape having the void portion, it was 1500 MPa or less. Moreover, the maximum tensile stress showed 1100 MPa or less by making the radius of a corner 15 mm or more.
From this result, it can be seen that the stress applied to the mold piece largely differs depending on the presence or absence of the void portion formed by the chamfered portion. In addition, it is also understood that the stress can be significantly reduced at a radius of 15 mm or more for the radius formed at the corner. Thereby, it is understood that the formation of the void portion can more reliably prevent the occurrence of the crack of the hot forging die.
In the present invention, it is also possible to make the base metal mold 3 and the mold piece 2 different metals. For example, the base metal mold 3 can be manufactured as a relatively inexpensive alloy tool steel, and the mold piece 2 can be made a Ni-based super heat-resistant alloy. Among alloyed tool steels, hot mold steels are preferable because they are excellent in high-temperature strength.
As an example of such a combination, it is also possible to make the entire surface of the working surface (mold engraving surface) a Ni-based super heat-resistant alloy, or a place to which a larger stress is applied at the time of hot forging It is also possible to use Ni-based super heat-resistant alloy mold pieces in places exposed to high temperatures sometimes, and at least one of the other mold pieces to be steel for hot molds. According to the former structure (the entire surface of the work surface is made of a Ni-based super heat resistant alloy), there is an advantage that the entire surface of the work surface can be strengthened. Moreover, it is economical compared to the case of manufacturing a one-piece hot forging die made of a Ni-based super heat-resistant alloy. In the latter case, if a mold piece having a Ni-based super heat-resistant alloy is disposed at a place where the wear resistance and heat resistance of the hot forging die at the time of hot forging are particularly required, It is economical and particularly preferable because it improves the life and uses less expensive hot mold steel.
Further, since hot forging die of the present invention is composed of a plurality of mold pieces, for example, when using the Ni-base superalloy as die piece, the solution treatment and aging treatment The strength can be increased to further enhance the wear resistance and heat resistance, and the life of the mold can be improved. In particular, when a large forged product of several tens of thousands of tons is produced by hot forging, the die for hot forging itself is enlarged, so that the entire die is subjected to solution treatment and aging treatment, It is necessary to prepare a large heat treatment furnace. In addition, when the solution treatment temperature of the Ni-based super heat-resistant alloy is applied to the alloy tool steel, the alloy tool steel is softened. In the case of the present invention, even if different metals are used, it is possible to apply optimal heat treatment individually to apply heat treatment that can maximize the characteristics of the alloy.
In the present invention, the Ni-based heat-resistant alloy layer may be coated on the highly engraved mold surface 4. The coating of the Ni-based super heat-resistant alloy layer on the engraved surface 4 improves the wear resistance and can also be expected to have a heat retaining effect on the engraved surface. In addition, as a coating method of a Ni super heat-resistant alloy layer, for example, since the Ni super heat-resistant alloy layer can be adjusted to any thickness by using build-up welding, it is particularly preferable.
Further, in the present invention, since the mold pieces are prepared individually, it is possible to reduce the mold manufacturing cost particularly when hot forging a large product. For example, the application to the hot forging of a large-sized turbine blade material is effective.
The above-mentioned alloy tool steel material may be, for example, one defined by JIS-G4404. Among them, C: 0.25 to 0.5%, N: over 0: 0.03% or less, Si: over 0:% by mass as a typical component range for use in hot 1.2% or less, Mn: more than 0 and 0.9% or less, Al: 0 to 0.5%, P: 0 to 0.03%, S: 0 to 0.01%, V: 0 to 2 1%, Cr: 0.8 to 5.5%, Ni: 0 to 4.3%, Cu: 0 to 0.3%, Mo: 0 to 3.0%, W: 0 to 9.5% Preferably, an alloy containing Co: 0 to 4.5%, the balance being Fe and impurities.
The Ni-based super heat resistant alloy referred to in the present invention is, for example, an alloy corresponding to UDIMET 520 (UDIMET is a registered trademark of Special Metals), an alloy corresponding to Udimet 720, an alloy equivalent to Waspaloy, an alloy corresponding to Alloy 718, etc., Al, Ti, Nb, etc. An alloy mainly composed of Ni capable of precipitation strengthening of intermetallic compounds.
And in this invention, it is preferable that the mold piece mentioned above is mounted in a base metal mold by shrink fitting. This is because when the mold piece and the base metal mold are integrated by shrink fitting, they can be integrated firmly.
The use of hot forging die of the present invention described above, it becomes possible to high mold manufacturing yield, obtained hot forged material having a desired surface form can also be stabilized quality. Also, if a mold piece of high strength material is provided and placed in a place including the stress concentration portion of the forging pressure, it is possible to prevent problems such as cracking of the mold during hot forging.
Further, when the Ni-based super heat-resistant alloy layer is formed on the working surface side of the mold piece to be used, the life of the mold can be further improved. In addition, since it is possible to form a Ni-based super heat resistant alloy layer for each mold piece, there is no need to particularly increase the size of a build-up welder that forms a Ni-based super heat resistant alloy layer. is there.
Hot forging die of the present invention, even when manufacturing a forged material for large turbine blades, it is possible to more reliably prevent the cracking of the hot forging die used therefor.
Reference Signs List 1 mold for hot forging 2 mold piece 3 base metal mold 4 mold engraving surface 11 chamfered portion 12 void portion 13 corner portion 14 corner portion 15 step portion

Claims (2)

  1. A hot forging die for a turbine blade, wherein an assembly of a plurality of die pieces joined together to form an integral body is mounted as a core in a base die,
    The hot forging die comprises a die-cut surface in the form of the turbine blade,
    The engraving surface is composed of the plurality of mold pieces,
    Wherein when viewed engraved surface of the turbine blade shape from above, in so that such a diagonal to the longitudinal direction of the dividing line of the plurality of mold pieces in engraved surface of the turbine blade shape, the plurality A mold for hot forging characterized in that the mold pieces of (1) are joined.
  2.   The mold for hot forging according to claim 1, wherein at least one of the mold piece and the base metal mold is coated with a Ni-based super heat-resistant alloy layer on the working surface side.
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JPS586744A (en) * 1981-07-01 1983-01-14 Toyota Motor Corp Die with elliptic internal die hole
JPH0133263B2 (en) * 1983-05-23 1989-07-12 Mitsutoyo Kiko Kk
JPS623845A (en) * 1985-06-28 1987-01-09 Masahiro Yokoi Cold pressing tool
DE69422424T2 (en) * 1993-12-17 2000-08-03 Wyman Gordon Co Tiered, segmented forge with closed die
JP3857897B2 (en) * 2001-09-21 2006-12-13 新キャタピラー三菱株式会社 Mold reassignment device and mold reassignment method
RU2220020C1 (en) * 2002-04-04 2003-12-27 Открытое акционерное общество "Чепецкий механический завод" Method of manufacture of forgings, predominantly out of metals and alloys of titanium subgroup and forging complex for performing the same
DE102007032804B3 (en) * 2007-07-10 2008-09-04 V&M Deutschland Gmbh Forging mandrel for hot-forging of tubular work-pieces made of metal has a mandrel body made from heat-resistant material and a mandrel rod
GB0915949D0 (en) * 2009-09-11 2009-10-28 Rolls Royce Plc A die former
KR20110038774A (en) * 2009-10-09 2011-04-15 정연수 Split die for forming bolt head or nut
JP6311969B2 (en) * 2013-03-28 2018-04-18 日立金属株式会社 Die for hot forging and hot forging method
JP6028678B2 (en) * 2013-05-29 2016-11-16 トヨタ紡織株式会社 Molding equipment

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