JP6558565B2 - Hot forging die equipment - Google Patents

Description

  The present invention relates to a hot forging die apparatus.

In recent years, the demand for hot stamping and forging products for medium and large aircrafts has increased greatly. Among these hot stamping and forging products for medium and large aircraft, for example, the turbine disk of an aircraft jet engine is made of a nickel-based super heat-resistant alloy or a titanium alloy, and is concentric and has a size exceeding 1 meter in diameter. . In order to manufacture these large forgings, the deformation load during hot stamping forging requires a very large pressing force exceeding 150MN. For example, recently, a large-scale hot forging apparatus of 50,000 tons class has begun to operate, and a hot forging die used for the large-scale hot forging apparatus has also been enlarged.
As a hot forging die most suitable for the large-scale hot forging apparatus, for example, International Publication No. WO2013 / 147154 pamphlet (refer to Patent Document 1) proposed by the applicant of the present application includes hot forging a material to be forged. As the hot forging die for forging, the hot forging die has a plurality of ring-shaped die pieces concentrically combined and fixed, and the axial direction of the ring-shaped die piece Is the pressing direction when forging the forging material, and a die engraving surface is formed on the portion of the hot forging die that contacts the forging material, and a built-up layer of a nickel-based superalloy is formed. There is an invention of a hot forging die.

International Publication No. WO2013 / 147154 Pamphlet

According to the above-mentioned invention of Patent Document 1, it is possible to manufacture a mold with a high yield, and to a large-sized aircraft jet engine disk that has been difficult to manufacture in the past, and a hot stamping and forging mold for a gas turbine disk for power generation. This makes it possible to manufacture a large-sized die-forged product that is inexpensive and of high quality, together with a long die life.
By the way, the hot forging die used in the large-scale hot forging apparatus of 50,000 tons class may have a total weight exceeding 30 tons. For example, when performing hot forging including constant temperature forging and hot die forging using a hot forging die having such a weight, the hot forging die and the intermediate table used in combination with it are also enlarged. The problem that the temperature drop (heat removal) of the molding surface (work surface) of the hot forging die was severe occurred. It is advantageous to maintain the temperature of the hot forging die to a certain level because the forging load can be lowered in addition to improving the life of the hot forging die.
An object of the present invention is to provide a hot forging die device capable of suppressing a temperature drop of the hot forging die in a large hot forging die device.

The present invention has been made in view of the above-described problems.
That is, the present invention provides an upper mold set including an upper mold die holder and an upper mold, a lower mold set including a lower mold die holder and a lower mold, and the upper mold set and the lower mold set. A hot forging die device comprising an upper die set holding part and a lower die set holding part for holding each,
The upper mold includes a molding surface, a bottom surface facing the upper mold set holding section, and a pressing section that contacts the upper mold die holder and restrains the upper mold, and the pressing section and the upper mold In contact with the die holder, the upper mold is fixed to the upper mold set holding part via the upper mold die holder, and the part where the pressing part and the upper mold die holder are in contact with each other With a gap that suppresses heat transfer from the upper mold,
The lower mold includes a molding surface, a bottom surface facing the lower mold set holding section, and a pressing section that contacts the lower mold die holder and restrains the lower mold, and the pressing section and the lower mold The lower die is fixed to the lower die set holding portion via the lower die die holder, and the portion where the pressing portion and the lower die die holder are in contact with each other is in contact with the die holder. This is a hot forging die apparatus having a void portion that suppresses heat transfer from the lower die.
Preferably, between the outer peripheral surface of the upper mold and the inner peripheral surface of the upper mold die holder of the hot forging die device, and between the outer peripheral surface of the lower mold and the lower mold die holder. It is a die device for hot forging provided with a gap between the peripheral surface.
More preferably, the upper die of the hot forging die device is an assembly of a plurality of die pieces, and the lower die is an assembly of a plurality of die pieces. This is a hot forging die apparatus.
More preferably, an upper mold laying plate is provided on the upper mold set holding part side of the upper mold of the hot forging die apparatus, and a lower mold is provided on the lower mold set holding part side of the lower mold. It is a hot forging die apparatus provided with a mold floor.
More preferably, the height of the upper die of the hot forging die device or the height of the upper die die holder is lower than the total height of the upper die and the upper die base plate, and ,
The surface of the upper mold protrudes to the lower mold side from the surface of the upper mold die holder on the side facing the lower mold die holder,
The upper mold die holder is not in contact with the upper mold set holding part,
The height of the lower mold, or the height of the lower mold die holder is lower than the total height of the lower mold and the lower mold floor, and
The surface of the lower mold protrudes to the upper mold side from the surface of the lower mold die holder on the surface side facing the upper mold die holder,
The lower mold die holder is a hot forging mold apparatus that is not in contact with the lower mold set holding portion.
More preferably, the gap portion of the hot forging die device has a groove shape, and the cross-sectional shape of the gap portion is a semicircular shape, a V shape having a curved surface shape, and a rectangular shape having a curved surface shape. It is a die device for hot forging which is one of the letter shapes.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to suppress the temperature fall of the hot forging die in a large sized hot forging die apparatus. Therefore, when hot forging is performed using the die device for hot forging according to the present invention, the temperature drop of the die can be suppressed, so that the forging load can be reduced, and a homogeneous hot forged product is efficiently produced. It becomes possible.

It is a cross-sectional schematic diagram which shows an example of the die apparatus for hot forging of this invention. It is a cross-sectional schematic diagram which shows the temperature measurement position of the space | gap part which suppresses the heat transfer from the metal mold | die provided in the die apparatus for hot forging of this invention. It is a figure which shows a heat transfer analysis result. It is a schematic diagram which shows an example of the cross-sectional shape of a recessed part among the uneven | corrugated | grooved parts of the metal mold | die for hot forging of this invention. It is a schematic diagram which shows an example of the formation place of a space | gap part.

The present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an example of a hot forging die device of the present invention. FIG. 1 shows a hot forging die comprising an upper die set 3 comprising an upper die die holder 1 and an upper die 2, and a lower die set 5 comprising a lower die die holder 21 and a lower die 4. The device is shown.
The upper mold 2 has a molding surface in which a desired shape is formed on the surface that presses the forging material during forging, and has a bottom surface as a surface facing the upper mold set holding portion 6. A holding part 19 that comes into contact with the die holder 1 is provided. The lower mold 4 has a molding surface in which a desired shape is formed on the surface that presses the forging material during forging, and has a bottom surface as a surface facing the lower mold set holding portion 7. The holding part 19 which contacts the die die holder 21 is provided.
The upper mold die holder 1 holds the upper mold 2 from the side by bringing the pressing part 19 formed on the upper mold 2 into contact with the upper mold die holder 1, and the lower mold die holder 21 is the lower mold 4. By holding the pressing portion 19 formed on the lower die die holder 21 in contact with the pressing die 19 from the side surface side. The upper mold die holder 1 and the lower mold die holder 21 are configured so that no forging load is applied during hot forging. The upper mold 2 is fixed to the upper mold set holding section 6 and the lower mold 4 is fixed to the lower mold set holding section 7 through the upper mold die holder 1 and the lower mold die holder 21 as follows. Fixed.
The upper mold set 3 and the lower mold set 5 are held by an upper mold set holding unit 6 and a lower mold set holding unit 7, respectively. In FIG. 1, the upper mold set holding unit 6 and the lower mold set holding unit 7 are shown as an intermediate stage, and an upper mold set 3 and a lower mold set 5 are constituted by a clamp 8 and a positioning fastening part (not shown). Are held on the intermediate platform (upper mold set holding unit 6, lower mold set holding unit 7). Specifically, a clamp is locked to the outer peripheral side of the upper mold die holder 1 and the lower mold die holder 21, and the upper mold set 3 is moved to the upper mold set holding portion 6 by the clamp and positioning fastening parts. The lower mold set 5 is fixed to the lower mold set holding portion 7. When the intermediate base (upper mold set holding unit 6, lower mold set holding unit 7) is not provided, the hot forging device main body is directly held by the hot forging device main body and the upper mold set holding unit 6 and the lower mold set holding unit 6. The mold set holding unit 7 is obtained.
The “upper mold set, lower mold set” in the present invention refers to an assembly of the upper mold 2 or the lower mold 4 and the die holder (1 or 21). "Apparatus" refers to a mold apparatus provided with the above-described pair of upper mold set and lower mold set.

Further, the “upper mold” and the “lower mold” referred to in the present invention may be a single body or an assembly formed by combining a plurality of mold pieces. In any structure, the work surface having the forging material in a predetermined shape has a molding surface in which the predetermined shape is engraved.
In FIG. 1, the upper and lower mold laying plates (11, 22), the mother mold 12, A structure having at least three mold pieces of the mold 13 is shown. In this case, the upper and lower mold laying plates (11, 22) uniformly apply loads to the upper mold set holding unit 6 and the lower mold set holding unit 7 during hot forging. 22) the contact surface product of the surface that contacts the bottom surface of the mother die 12 may shall be the one having a higher area of the bottom surface of the mold 12. Moreover, the manufacturing cost of an upper metal mold | die and a lower metal mold | die can be reduced by making the material of an upper and lower metal mold | die board (11,22) into a material cheaper than a mother mold. Also, the mother mold 12 and the mold 13 are divided into one part for easy manufacturing, and another part is to divide the mother mold and the mold into This is because it becomes easier to preheat each die before forging.
For example, when the mother die and the forming die are integrated, if they are used in a large-scale hot forging device, the weight increases and the preheating time is significantly increased. Therefore, by dividing, the time for raising the mold temperature to a predetermined preheating temperature can be shortened. For example, when the mother die and the mold are made of different materials, the preheating temperature can be set individually. In addition, when an assembly of split dies (a plurality of mold pieces) is used, the molding die to which a large forging load is applied is made of a high-strength material, and the other mother mold and the upper and lower mold laying boards are slightly stronger than the molding dies. It is also possible to configure it with an inexpensive material. This is preferable because it can reduce the cost of mold production.
The cross-sectional shape of the upper mold and the lower mold should be such that the shape gradually decreases from the molding surface (working surface) including the mold toward the upper mold set holding unit 6 and the lower mold set holding unit 7. Should. This is because the hot forging die apparatus targeted by the present invention is used for a large-scale hot forging apparatus with a scale of tens of thousands of tons, so that the upper mold is formed from the molding surface (working surface) provided with the molding die. If the shape gradually decreases toward the set holding part 6 and the lower mold set holding part 7, local stress is generated in the upper and lower base plates and the upper and lower mold set holding parts. Because it becomes easy to destroy.

In the present invention, the upper die 2 and the lower die 4 are brought into contact with the upper die 2 and the die die holders 1 and 21 by contacting the pressing portion 19 formed on the upper die 2 and the lower die 4 with the die holder. (Specifically, it is fixed to the upper die set holding portion and the lower die set holding portion via a clamp 8 and a positioning fastening part (not shown)), and the portion where the pressing portion and the die holder are in contact with each other. Has a gap 9 that suppresses heat transfer from the mold. The gap 9 suppresses heat transfer from the upper mold and the lower mold (suppresses heat removal), and suppresses a temperature drop of the upper mold and the lower mold. In addition, the holding | suppressing part in which this space | gap part 9 is provided is a place where a forge load is not directly applied at the time of hot forging, and is preferable as a place where the space | gap part 9 is provided.
Moreover, in this invention, it is preferable to provide the clearance gap part 10 between the outer peripheral surface of the upper metal mold | die 2 and the lower metal mold | die 4, and the internal peripheral surface of the upper and lower mold die holders 1 and 21. FIG. One of the reasons is that the die holder used in the large-scale hot forging apparatus has a large size and weight. Therefore, by providing the gap portion 10 to reduce the amount of heat removed from the upper mold and the lower mold to suppress the temperature rise of the die holder, the temperature decrease of the upper mold and the lower mold can be suppressed. In addition, when the upper die and the lower die are expanded by heat during hot forging or during heat retention before hot forging, the gap portion 10 functions as a buffer portion, and the upper and lower die holders 1, The stress applied to the inner side of 21 can be reduced. Further, during hot forging, the upper die and the lower die are deformed by a large forging stress, but the presence of the gap portion 10 can prevent the die holder from being deformed and suppress the life reduction of the upper and lower die die holders. be able to. Moreover, it is not necessary to manufacture the die holder with a high-strength material, and the manufacturing cost of the die holder can be reduced.
Therefore, it is preferable that the gap portion 10 has a space that can maintain the gap portion even during hot forging, and suppresses the temperature rise, and the upper die, the lower die, and the upper and lower die die holders. In consideration of the thermal expansion of the upper mold and the lower and upper upper molds, the outer peripheral surfaces of the upper mold 2 and the lower mold 4 and the inner peripheral surfaces of the upper and lower mold die holders 1 and 21 are taken into consideration. It is preferable to provide a gap 10 of about 1 to 40 mm. The width of the gap is preferably changed according to the size of the upper mold. For example, if the diameter of the upper mold is about 1000 to 2000 mm, it is about 1 to 20 mm, and if the diameter of the upper mold exceeds 2000 mm, it is 5 It is good to be about ~ 40 mm. In order to maintain a uniform gap between the outer peripheral surface of the upper mold 2 and the inner peripheral surfaces of the upper and lower mold die holders 1 and 21, in the present invention, the upper mold is placed at a predetermined position by a positioning fastening component (not shown). It is better to fix the mold.

Here, the heat removal suppression effect by the space | gap part 9 and the clearance gap part 10 with which the holding | suppressing part 19 of this invention was equipped is shown.
In the two molds shown in FIG. 2, the mold A corresponds to the upper mold 2 or the lower mold 4. The mold B corresponds to the die holder (1 or 21). In FIG. 2, a gap 10 is provided between the outer peripheral surface of the upper mold 2 or the lower mold 4 and the inner peripheral surface of the die holder (1 or 21) in addition to the gap portion 9. The cross-sectional shape of the gap portion 9 provided in the holding portion 19 is a semicircular shape having a radius of 5 mm, and three gap portions were formed by cutting along the holding portion 19 of the mold A. Moreover, the clearance gap provided in the outer peripheral surface of the metal mold | die A and the internal peripheral surface of the metal mold | die B was 10 mm. Here, although the cavity is formed in the mold A, the cavity may be formed in the mold B, or the cavity may be formed in both the mold A and the mold B.
Then, the mold A was heated to 450 ° C. The mold B is not heated, and the temperature before the test of the mold B is 20 ° C. Then, the mold A was fitted into the mold B, and the temperature change of the mold B was measured for 10,000 seconds. The temperature change measurement points are the four points shown in FIG. During the test, the mold A is in contact with the mold B at the pressing portion, and heat exchange is performed at this portion. In addition, as a comparative example, a test in which a gap and a gap were not provided was also tested under the same conditions. The results are shown in FIG. 3 (FIG. 3A is the present invention, and FIG. 3B is a comparative example).
The measurement point P2 is a point where the mold A and the mold B are in direct contact. As for the measurement result of P2, in the comparative example, the temperature was raised to 200 ° C. all at once, and the temperature was 50 ° C. even after 10000 seconds (after 2.7 Hr) of the measurement. On the other hand, in P2 of the present invention provided with voids, the temperature was increased to 190 ° C. at a stretch, and then the temperature rapidly decreased. For example, the temperature drop time up to 60 ° C. was 7350 seconds (2.12 Hr) in the comparative example, compared with 6350 seconds (1.76 Hr) in the present invention. Further, the effect of providing the gap portion can also be understood from the fact that the temperature rise is smaller in the present invention at other measurement positions. Comparing the temperature change of FIG. 3A of the present invention with the temperature change of FIG. 3B of the comparative example, the temperature of the mold B is clearly higher in the comparative example having no gap and no gap. I understand that. Thereby, it turns out well that heat transfer from the mold A to the mold B can be suppressed by providing the gap and the gap. In addition, P2 is a measurement result of the place where the metal mold | die A and the metal mold | die B are contacting as mentioned above. It can be seen that both the present invention and the comparative example are provided with a gap, and if the gap exists, the temperature rise of the mold B can be remarkably suppressed.

By the way, it is preferable to form the place where the gap is formed with two different ideas. The first is to form voids in common parts. For example, the upper and lower mold die holders 1, 21 and the upper and lower mold laying plates 11, 22 are members that can be used together even if the target hot forged product changes. The part 9 is to be formed. In other words, a gap is formed on the part side of the upper mold 2 and the lower mold 4 where, for example, the mother mold 12 contacts. FIG. 5 shows a schematic diagram in which a gap 9 is provided on the upper and lower mold die holders (1, 21) side. Thereby, in the case of forging products having different final shapes, the function of suppressing heat transfer is maintained even if only the mold (for example, the mother die 12) having a different die shape formed on the molding surface is changed. Can do.
The second is to form the gap 9 on the material side with high strength. When the proportion of the portion where the void portion is formed becomes large, a large load is applied to the mold particularly during hot forging of tens of thousands of tons. It is to form a void in a component on the higher strength side so that a decrease in strength can be kept low even if a void is formed. In this case, the strength is often high for the upper and lower mold die holders, and the upper and lower mold bases are often the mother mold. Therefore, it is also possible to form a gap on the mold side (matrix side). Of course, when the upper and lower mold die holders 21 and 21 and the upper and lower mold floor plates 11 and 22 are made of a material stronger than the mold, the upper and lower mold die holders 1 and 21 and the upper and lower mold floor plates 11 and 22 are formed. A void portion may be formed. For example, even when the strength of the mold is the highest, avoid formation of a void at a position where a large forging load is directly applied, and in terms of mold production cost, a void is formed on the mold side. When manufacturing, since it is necessary to process for every metal mold | die, expense increases. Therefore, it is preferable to provide a gap on the upper and lower mold die holder sides as much as possible.
Which method should be selected may be selected in consideration of forging load, product shape, and the like.

In the present invention, the ratio of the formed gap is, for example, in the case of the bottom side of the upper mold or the lower mold where a forging load is directly applied, the contact area between the mold and the intermediate table, and the upper and lower molds. It is good to set it as 5 to 50% of the contact area of a mold base plate and a mother mold. This is because the heat transfer suppression effect is improved as the proportion of the recesses forming the voids increases, but the forging received at the time of hot forging on the bottom surface side of the mold (upper and lower mold sheet contact surface side in FIG. 1). This is because the load is large and the strength of the hot forging die may be reduced. Further, since the forging load at the time of hot forging is lower than that on the bottom surface side of the mold at the pressing portion on the side surface side of the mold (on the die holder contact surface side in FIG. 1), the void portion of the contact area with the mold It is good also considering the ratio which occupies as a range exceeding 50%.
As the form of the gap, for example, on the bottom side of the upper mold 2 and the lower mold 4 (on the upper and lower mold floor contact surface side in FIG. 1), for example, the upper mold 2 and the lower mold 4 When looking at the bottom surface, various shapes such as a linear shape, a circular shape, a lattice shape, and a rectangular shape can be selected. The shape is preferably determined in consideration of ease of processing, strength, and the like. Moreover, the process of a space | gap part can be processed into either one of the members which oppose, or can be processed into both members.

As shown in FIG. 4, the cross-sectional shape of the gap 9 formed in the present invention was a groove-shaped semicircular shape (FIG. 4A), a U-shape with a curved surface shape (FIG. 4B), and a curved surface shape. It is preferably one of V shapes (FIG. 4C). What is common to this shape is a shape to which a radius without a sharp point is given. If there is a pointed part, stress tends to concentrate and there is a risk of becoming the starting point of fracture. Therefore, in order to reduce the stress concentration portion, it is preferable to use a curved shape or a combination of a curved shape and a flat shape. In addition, it is good to determine which shape should be considered in consideration of ease of processing.
In addition, a depth of the gap is about 0.5 to 5 mm. Since the heat transfer preventing effect is more affected by the ratio of forming the void than the depth of the void, it is not necessary to excessively increase the depth of the void.

Also, as shown in FIGS. 1 and 2, the height of the upper mold 2 (when there is no upper mold base plate 11) or the total height of the upper mold 2 and the upper mold base plate 11. The height of the upper mold die holder 1 is low, and the surface of the upper mold 2 protrudes to the lower mold side from the surface of the upper mold die holder 1 on the side facing the lower mold die holder 21; Furthermore, it is preferable that the upper mold die holder is not in contact (not shown) with the upper mold set holding portion (intermediate base) 6. This non-contact means that the upper mold die holder holds the upper mold and is fixed to the intermediate base (upper mold set holding portion) by the clamp and the positioning fastening member. It means that it is fixed without contacting the intermediate platform. Similarly, on the lower mold side, the height of the lower mold 4 (in the case where the lower mold floor 22 is not provided) or the total height of the lower mold 4 and the lower mold floor 22 is lower than the lower mold 4. The height of the die die holder 21 is low, and the surface of the lower die 4 protrudes into the upper die from the surface of the lower die die holder 21 on the side facing the upper die die holder 1 (see FIG. The broken line indicated by 2 indicates the position of the mold surface and protrudes from the surface of the die holder), and the lower mold die holder 21 is not in contact with the lower mold set holding portion 7 (not shown). It is preferable.
This is so that the upper and lower mold die holders 1 and 21 are not subjected to a forging load during hot forging. For example, the height of the die holder is the upper mold 2 or the lower mold 4 (in the case where the upper and lower mold floors 11 and 22 are provided, the upper and lower mold floors are added in addition to the upper and lower mold floors. If it is higher than (height), the die holder may receive a hot forging load during hot forging. If so, the die holder may be destroyed, and the height of the die holder is determined by the upper mold or the lower mold (in the case where the upper and lower mold base plates 11 and 22 are provided, in addition to the height of the upper mold and the lower mold) 2-10 mm lower than the height of the upper and lower mold slabs, and the upper and lower mold die holders are left in contact with the upper mold set holding part 6 and the lower mold set holding part 7 and completely It is preferable to have a structure that does not receive a load during hot forging.
Thereby, it can prevent reliably that a die holder receives the forge load at the time of hot forging.
As described above, according to the large-sized hot forging die device of the present invention to be described, it is possible to suppress the temperature drop of the hot forging die.

1 Upper mold die holder 2 Upper mold 3 Upper mold set 4 Lower mold 5 Lower mold set 6 Upper mold set holding part (intermediate stand)
7 Lower mold set holder (intermediate stand)
8 Clamp 9 Cavity 10 Clearance 11 Upper Mold Base 12 Mother Mold 13 Mold 19 Pressing Part 21 Lower Die Holder 22 Lower Mold Base

Claims (5)

An upper mold set including an upper mold die holder and an upper mold, a lower mold set including a lower mold die holder and a lower mold, and an upper mold holding each of the upper mold set and the lower mold set A mold apparatus for hot forging comprising a mold set holding part and a lower mold set holding part,
The upper mold includes a molding surface, a bottom surface facing the upper mold set holding unit, and a pressing unit that contacts the upper mold die holder, and the pressing unit and the upper mold die holder are in contact with each other, The upper mold is fixed to the upper mold set holding part via the upper mold die holder, and heat transfer from the upper mold is performed at a portion where the pressing part and the upper mold die holder are in contact with each other. With a gap to suppress
The lower mold includes a molding surface, a bottom surface facing the lower mold set holding unit, and a pressing unit that contacts the lower mold die holder, and the pressing unit and the lower mold die holder are in contact with each other, The lower mold is fixed to the lower mold set holding part via the lower mold die holder, and heat transfer from the lower mold is performed at a portion where the pressing part and the lower mold die holder are in contact with each other. comprising suppressing void portion,
A gap of 1 to 40 mm between the outer peripheral surface of the upper mold and the inner peripheral surface of the upper mold die holder, and between the outer peripheral surface of the lower mold and the inner peripheral surface of the lower mold die holder. Part
The surface of the upper mold protrudes to the lower mold side from the surface of the upper mold die holder on the side facing the lower mold die holder,
The upper mold die holder is not in contact with the upper mold set holding part,
The surface of the lower mold protrudes to the upper mold side from the surface of the lower mold die holder on the surface side facing the upper mold die holder,
The hot forging die apparatus, wherein the lower die holder is not in contact with the lower die set holding portion . The said upper metal mold | die is an assembly body by the combination of a some metal mold | die piece, The said lower metal mold | die is an assembly body by the combination of a some metal mold | die piece, The Claim 1 characterized by the above-mentioned. Molding equipment for hot forging. Comprising a upper die decking on said die set holder side of the upper die, according to claim 1 or characterized in that it comprises a lower die decking to said lower mold set holding portion of the lower die 2. A die device for hot forging as described in 2 . The height of the upper mold, or the height of the upper mold die holder is lower than the total height of the upper mold and the upper mold base plate ,
The lower tool height, or to any one of claims 1 to 3 than the total height of the lower die decking and the lower tool, characterized in that has a low height of the lower tool die holder The hot forging die apparatus as described. The gap portion is groove-shaped, and a cross-sectional shape of the gap portion is any one of a semicircular shape, a V shape having a curved surface shape, and a U-shape having a curved surface shape. Item 5. A hot forging die device according to any one of Items 1 to 4 .