Method for forging titanium material

Abstract

To provide a method for cogging a titanium material by which the yield of the titanium material is improved.SOLUTION: A titanium material cogging method for reducing the diameter of a titanium material having a columnar shape and extending from a first side to a second side by using a forging die includes holding the titanium material, heating the titanium material, and starting cogging of the titanium material by the forging die from an end portion of the titanium material in a longitudinal direction. The length of the cogging surface along the longitudinal direction is 0.5 times or more and 3 times or less the diameter of the titanium material. At the start of cogging, the position of the first end portion in the longitudinal direction with respect to the first die end portion is between a first position at which the first end portion is retracted by a retraction length to the second side with respect to the first die end portion and a second position at which the first end portion protrudes by a protrusion length to the first side with respect to the first die end portion. The drawing-in length is ≤ 0.2 times the length of the cogging face, and the projecting length is ≤ 0.2 times the diameter of the titanium material.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for forging titanium material. [Background technology]

[0002] Patent Document 1 discloses a method for producing a titanium material for sputtering. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4990531 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method for manufacturing titanium material disclosed in Patent Document 1, a titanium ingot, which is the starting material, is subjected to multiple forging and stretching processes to reduce its diameter and then finish forged into a cylindrical shape with a predetermined outer diameter. In the forging and stretching processes, the titanium material is forged by grasping one end of the titanium material with a manipulator and forging and stretching the titanium material in the longitudinal direction using a forging die. In this forging and stretching method, there is no clearly established know-how regarding the start position of the forging and stretching process on the forging die, and the start position of the forging and stretching process may vary depending on the worker.

[0005] For example, one worker may begin forging the titanium material from one end held by a manipulator toward the other end. Another worker may begin forging from an intermediate position between the two ends. In this type of forging method, the titanium material may bend during the forging process, preventing it from being formed into the desired shape. This may result in a reduction in the yield of the titanium material, since a process of adjusting the shape of the titanium material to the desired shape is required.

[0006] The object of the present invention is to provide a method for forging titanium material that can improve the yield of titanium material. [Means for solving the problem]

[0007] The present disclosure provides: A titanium material forging method for reducing the diameter of a columnar titanium material extending from a first side to a second side using a forging die, the titanium material forging method comprising: gripping the titanium material; heating the titanium material; The forging of the titanium material by the forging die is started from an end portion in the longitudinal direction of the titanium material. The present invention provides a method for forging and stretching a titanium material, comprising the steps of:

[0008] According to the titanium material forging and stretching method of the present disclosure, by starting the forging and stretching from the end of the titanium material, it is possible to suppress shape defects due to bending of the titanium material, and as a result, it is possible to improve the yield of the titanium material. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows a side view of the arrangement of a titanium material, a forging die, and a manipulator in a titanium material forging process according to this embodiment. FIG. [Figure 2] 1 shows a longitudinal view of an example of a forging and elongation process for a titanium material according to an embodiment of the present invention. [Figure 3] 10A and 10B are views showing another example of the forging process of the titanium material according to the present embodiment as viewed from the longitudinal direction. [Figure 4] 1 is a side view showing an example of a forging process for a titanium material according to an embodiment of the present invention. [Figure 5] 10A and 10B are side views showing another example of the forging process of the titanium material according to the present embodiment. [Figure 6] An example of the shape of titanium material before and after forging is shown below. [Figure 7] 4 shows other examples of the shape of titanium material before and after forging. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0011] Figure 1 shows a side view of the arrangement of a titanium material 1, a forging die 2, and a manipulator 3 during the forging-extension process of the titanium material 1. Figure 1 shows the arrangement of the titanium material 1 at the start of forging-extension. In Figure 1, the left-right direction is the X direction, the up-down direction is the Y direction, and the right side, left side, upper side, and lower side are referred to as the first side, second side, third side, and fourth side, respectively. First, each component used in the forging-extension process will be described with reference to Figure 1.

[0012] In FIG. 1, the titanium material 1 is illustrated as a columnar shape extending from a first side to a second side. The cross-sectional shape of the titanium material 1 can be circular, elliptical, or polygonal (see, for example, FIGS. 2 and 3). The cross-section of the titanium material 1 has a predetermined diameter D1. When the cross-sectional shape of the titanium material 1 is elliptical, the diameter D1 refers to the major axis of the ellipse. When the cross-sectional shape of the titanium material is polygonal, the diameter D1 refers to the length of the longest diagonal of the polygon.

[0013] The titanium material 1 has a first end 10 on a first side, a second end 11 on a second side, and a forged surface 12 that extends between the first end 10 and the second end 11 and is configured as a side surface of the titanium material 1. The forged surface 12 is a surface that is forged and stretched by a forging die 2 described below. In this specification, the longitudinal direction of the titanium material 1 means the X direction.

[0014] The titanium material 1 of this embodiment is a high-purity titanium material with a purity of 99.9% or more excluding gas impurities. Such a high-purity titanium material can be used as a thin film material. Specifically, the high-purity titanium material is used as a sputtering target in a sputtering method, which is a method for forming a thin film material.

[0015] A manipulator 3 is shown at the second end 11 of the titanium material 1. The manipulator is a machine equipped with a so-called robot arm for accurately moving an object to be forged. In this embodiment, the manipulator 3 grips the titanium material 1 at the second end 11. The manipulator 3 is movable in the X direction while gripping the titanium material 1. By moving the manipulator 3 in the X direction, the titanium material 1 can be forged and stretched at any position in the X direction by a forging die 2 (described below). The manipulator 3 can also rotate the titanium material 1 around the longitudinal axis of the titanium material 1 at any angle. This allows the cross-sectional shape of the titanium material 1 to be polygonal when forged and stretched by a flat die 2a (described below).

[0016] Two forging dies 2 are shown at a first end 10 of the titanium material 1. The forging die 2 of this embodiment has a forging surface 22 that contacts the titanium material 1, a first die end 20 on the first side, and a second die end 21 on the second side.

[0017] Here, the first and second die ends 20, 21 refer to the ends in the X direction of the forged surface 22. In other words, if the forging die has non-forged surfaces at both ends in the X direction that are not in contact with the titanium material 1 among the surfaces facing the titanium material 1, the ends of the non-forged surfaces are not the first and second die ends.

[0018] In the forging-extension process, the two forging dies 2 move back and forth in the Y direction many times, causing the forging-extension surface 22 to repeatedly collide with the forged-extension surface 12, thereby forging, i.e., forging-extension, the titanium material 1. The movement of the forging dies 2 is performed by, for example, a hydraulic press.

[0019] In the process of forming a cylindrical titanium material of a predetermined diameter as a finished product from a titanium ingot, which is the raw material, several types of forging dies 2 can be used. Figures 2 and 3 show forging dies 2 with different shapes. Figures 2 and 3 show the titanium material 1 and forging die 2 as viewed from the X direction.

[0020] The forging die 2 shown in Figure 2 is a flat die 2a with a flat forged surface 22. When forging a titanium material 1 using the flat die 2a, the titanium material 1 is rotated by a fixed angle with a manipulator 3 each time the forged surface 12 collides with the forged surface 22, so that the titanium material 1 is forged and stretched approximately evenly all around. As a result, the cross-sectional shape of the titanium material 1 becomes polygonal (see Figure 2(b)).

[0021] The forging die 2 shown in Figure 3 is a semicircular round die 2b whose forging surface 22 has a predetermined diameter. When forging and stretching a titanium material 1 using the round dies 2b, the titanium material 1 is sandwiched between two round dies 2b whose diameters are smaller than the diameter D1 of the titanium material 1, and the titanium material 1 is forged and stretched so that its diameter is reduced to the diameter of the round dies 2b (see Figure 3(b)). When forging and stretching using the round dies 2b, multiple round dies 2b with different diameters can be used depending on the target diameter.

[0022] In the process of forming the finished titanium material, a flat die 2a may be used in the first forging step, in which the titanium material is forged and stretched with the main purpose of destroying the cast structure of the titanium material. A round die 2b may be used in the second forging step, in which the titanium material is forged and stretched with the main purpose of finishing the diameter of the titanium material to the diameter of the finished titanium material. The types and selection methods of the forging dies are not limited to these. For example, a round die 2b may be used in the first forging step.

[0023] Next, the titanium material forging method of the present disclosure will be described with reference to FIGS. 4(a) to 4(e).

[0024] The arrangement of the titanium material 1, forging die 2, and manipulator 3 shown in Figure 4(a) is the same as that in Figure 1, i.e., the arrangement at the start of the forging process. The forging die 2 used in the forging process is selected so that the length L1 of the forging surface 22 in the X direction is 0.5 to 3 times the diameter D1 of the titanium material 1.

[0025] 4(a), the titanium material 1 is positioned so that the forging by the forging die 2 starts from a first end 10 of the titanium material 1. More specifically, the position of the first end 10 in the X direction relative to the first die end 20 is at a first position where the first end 10 is retracted by a retraction length L2 toward the second side relative to the first die end 20. In other words, the titanium material 1 is retracted by a retraction length L2 toward the second side relative to the first die end 20. The titanium material 1 is retracted relative to the first die end 20 so that the retraction length L2 is 0.2 times or less the length L1 of the forging surface 22.

[0026] Before placing the titanium material 1 as shown in Fig. 4(a), the titanium material 1 is heated to a predetermined temperature for forging. That is, the forging is so-called warm forging. The titanium material 1 is heated so that the surface temperature of the titanium material 1 at the start of forging is 500°C or higher and 850°C or lower.

[0027] In the state shown in Figure 4(a), the two forging dies 2 collide with the titanium material 1 in the Y direction multiple times, thereby reducing the diameter D1 of the titanium material 1 to a predetermined diameter D2 and forging it. The rate at which the titanium material 1 is compressed by the forging dies 2 (the so-called reduction amount) is set within the range of 7% to 50%. Figure 4(b) shows the state when the first end 10 of the titanium material 1 has been reduced to the diameter D2. In Figure 4(b), an extruded portion 13 is formed on a first side of the first end 10. The extruded portion 13 is formed by a portion of the forged titanium material 1 extending from the first end 10 to the first side.

[0028] Thereafter, the titanium material 1 is moved to the first side by the manipulator 3, and the portion of the titanium material 1 that has not yet been reduced in diameter is forged. Figure 4(c) shows the state in which the above steps are repeated and the forging position, i.e., the position of the forging die 2 relative to the titanium material 1, is located at approximately the middle position of the titanium material 1 in the X direction.

[0029] When the forging position reaches the intermediate position, as shown in FIG. 4( d ), the manipulator 3 releases its grip on the second end 11 and grips the first end 10. The titanium material 1 is then forged by the forging die 2 from the second end 11. The manipulator gripping the first end 10 may be different from the manipulator 3 that gripped the second end 11.

[0030] 4(d), the position of the second end 11 in the X direction relative to the second die end 21 is at a third position where the second end 11 is retracted by a retraction length L3 toward the first side relative to the second die end 21. In other words, the titanium material 1 is retracted by a retraction length L3 toward the first side relative to the second die end 21. The titanium material 1 is retracted relative to the second die end 21 so that the retraction length L3 is 0.2 times or less the length L1 of the forging surface 22.

[0031] When the second end 11 is forged in the state shown in Figure 4(d), a portion of the forged titanium material 1 extends from the second end 11 to the second side, as shown in Figure 4(e), and an extruded portion 13 similar to the extruded portion 13 on the first side is formed.

[0032] Thereafter, as shown in FIG. 4(e), the titanium material 1 is moved to the second side by the manipulator 3, and the portion of the titanium material 1 near the intermediate position that has not yet been forged is forged.

[0033] Through the forging and extending process described above, titanium material 1 with diameter D1 is forged and extended into a titanium material with diameter D2. The raw material, a columnar titanium ingot with a large diameter, is gradually reduced in diameter by repeating the forging and extending process multiple times, thereby forming a finished cylindrical titanium material with a predetermined diameter.

[0034] That is, in the forging and stretching process of this embodiment, the titanium material 1 is forged and stretched starting from one end (first end 10) toward the other end (second end 11), and when the forging and stretching position reaches approximately the middle position in the X direction, the titanium material 1 is forged and stretched from the second end 11 toward the first end 10, and the forging and stretching process is completed when the titanium material 1 is finally forged and stretched at approximately the middle position.

[0035] 5A and 5B show another example of the titanium material stretch forging method of the present disclosure, in which Fig. 5A shows the position at the start of the stretch forging.

[0036] 5(a), the titanium material 1 is positioned so that forging by the forging die 2 starts from a first end 10 of the titanium material 1. More specifically, the position of the first end 10 in the X direction relative to the first die end 20 is a second position where the first end 10 protrudes a protrusion length L4 toward the first side relative to the first die end 20. In other words, the titanium material 1 protrudes a protrusion length L4 toward the first side relative to the first die end 20. The titanium material 1 protrudes from the first die end 20 so that the protrusion length L4 is 0.2 times or less the diameter D1 of the titanium material 1.

[0037] Thereafter, similar to the forging and stretching method shown in Figure 4, the titanium material 1 is forged and stretched to the first side by the two forging dies 2, and when it has been forged and stretched to approximately the middle position of the titanium material 1, the grip of the second end 11 by the manipulator 3 is released, and the titanium material is forged and stretched from the second end 11.

[0038] 5(b) illustrates the arrangement of the titanium material 1, forging die 2, and manipulator 3 when the second end 11 is being forged. The position of the second end 11 in the X direction relative to the second die end 21 is a fourth position where the second end 11 protrudes a protrusion length L5 on the second side relative to the second die end 21. In other words, the titanium material 1 protrudes a protrusion length L5 on the second side relative to the second die end 21. The titanium material 1 protrudes relative to the second die end 21 so that the protrusion length L5 is 0.2 times or less the diameter D1 of the titanium material 1.

[0039] When the second end 11 is forged and stretched, the portion of the titanium material 1 near the intermediate position that has not yet been forged and stretched is forged and stretched, and the forging and stretching process ends. As a result, the titanium material 1 with diameter D1 is forged and stretched into a titanium material with diameter D2.

[0040] Here, "starting the forging and stretching of the titanium material from the first end of the titanium material" means that when the titanium material 1 is retracted toward the second side relative to the first die end 20, the forging and stretching starts from a range where the retraction length L2 is less than the length L1 of the forging and stretching surface 22, and when the titanium material 1 protrudes toward the first side relative to the first die end 20, the forging and stretching starts from a range where the protruding length L4 is 0.2 times or less the diameter D1 of the titanium material 1. Furthermore, "starting the forging and stretching of the titanium material from the second end of the titanium material" has the same meaning as above.

[0041] When forging titanium material from its midpoint toward its end, a portion of the titanium material is pushed out toward the unforged portion (the unforged portion). As a result, the shape of the unforged portion becomes distorted, and the titanium material may bend along its longitudinal direction. Forged titanium material in this state will not have the desired shape (e.g., a cylindrical shape with a perfectly circular cross section extending in a straight line). Therefore, workers must forge the titanium material again in a forging die to adjust its shape. As a result, it takes a long time to form titanium material with a specific diameter, which can reduce the yield of the titanium material. This phenomenon can also occur when forging titanium material from the portion held by the manipulator toward its end.

[0042] On the other hand, when forging and stretching titanium material from its end, as explained above, a portion of the titanium material is pushed outward from the end. As a result, the shape of the unforged and stretched portion is less likely to become distorted, and bending of the titanium material can be suppressed. This eliminates the need for workers to shape the titanium material, and can improve the yield of titanium material.

[0043] 6 and 7 show the states of the titanium material 1 before and after it is forged and stretched at the first end portion 10. In Fig. 6(a), the titanium material 1 is positioned so that the retraction length L2 is 0.2 times or less the length L1 of the forging and stretching surface 22. That is, in Fig. 6(a), the titanium material 1 is positioned with respect to the forging die 2 so that the reduction length (L1-L2 in Fig. 5) by the forging die 2 is sufficiently ensured.

[0044] In Fig. 7(a), the titanium material 1 is arranged so that the retraction length L2 is greater than 0.2 and equal to or less than 1 time the length L1 of the forging and extension surface 22. That is, in Fig. 7(a), the rolling length (L1-L2) is not sufficiently ensured compared to the embodiment shown in Fig. 6.

[0045] Figures 6(b) and 7(b) respectively show the shape of the titanium material 1 after forging. In Figures 6(b) and 7(b), an extruded portion 13 is formed at the first end portion. The extruded portion 13 shown in Figure 6(b) has a continuous shape that gradually protrudes toward the first side from the outer periphery toward the center of the titanium material 1. The extruded portion 13 shown in Figure 7(b) has a shape that protrudes toward the first side and is recessed toward the second side halfway as it moves from the outer periphery toward the center of the titanium material 1.

[0046] The phenomenon in which the extrusion portion 13 shown in Figure 7(b) is formed is called "rolling," and extrusion portions 13 having such a rolled shape must be cut off. To further improve the yield of the titanium material 1, the titanium material 1 is preferably forged and stretched to form the extrusion portion 13 shown in Figure 6(b) that does not have a rolled shape.

[0047] After extensive analysis, the inventors have found that the occurrence of entrapment can be suppressed by (a) setting the length L1 of the forged and extended surface 22 to be 0.5 to 3 times the diameter D1 of the titanium material 1, (b) positioning the first end 10 in the X direction relative to the first die end 20 between a first position where it is retracted by a predetermined retraction length L2 and a second position where it protrudes by a predetermined protrusion length L4, (c) setting the retraction length L2 to be 0.2 times or less the length L1 of the forged and extended surface, and (d) setting the protrusion length L4 to be 0.2 times or less the diameter D1 of the titanium material 1. Details of this are described below.

[0048] 6(b) and 7(b), the dotted areas indicate so-called dead zones A where elongation caused by the reduction of the forging die 2 is small. The dead zones A become smaller toward the radial center of the titanium material 1. In other words, the elongation of the titanium material 1 tends to be small near the outer periphery of the titanium material 1 and to increase toward the center.

[0049] The dead zone A changes depending on the frictional force acting between the titanium material 1 and the forging die 2 due to the reduction of the forging die 2. When the frictional force is large, the outer peripheral surface of the titanium material 1, i.e., the forged surface 12, adheres more firmly to the contact surface with the forging die 2, i.e., the forged surface 22. This reduces the elongation of the titanium material 1 at its outer periphery, and as a result, the dead zone A becomes larger. On the other hand, when the frictional force is small, the elongation of the titanium material 1 at its outer periphery becomes larger, and as a result, the dead zone A becomes smaller.

[0050] In this embodiment, the forging die 2 presses the titanium material 1 with a predetermined pressure. The fact that the reduction length (L1-L2) shown in FIG. 6 is longer than the reduction length (L1-L2) shown in FIG. 7 means that the reduction area of ​​the example shown in FIG. 6 is larger than the reduction area shown in FIG. 7. In other words, the force with which the forging die 2 in FIG. 6 presses the titanium material 1 is greater than the force with which the forging die 2 in FIG. 7 presses the titanium material 1. Since the value obtained by multiplying this pressing force by a predetermined friction coefficient corresponds to the friction force between the titanium material 1 and the forging die 2, the friction force in FIG. 6 is greater than the friction force in FIG. 7. Therefore, the dead zone A shown in FIG. 6(b) is larger than the dead zone A shown in FIG. 7(b).

[0051] The dead zone A shown in Fig. 6(b) extends from the outer periphery to near the center of the titanium material 1, while the dead zone A shown in Fig. 7(b) extends only near the outer periphery of the titanium material 1. Therefore, the extruded portion 13 shown in Fig. 6(b) gently protrudes toward the first side from the outer periphery toward the center, and the protruding length is shorter than the protruding length of the extruded portion 13 shown in Fig. 7(b).

[0052] The extruded portion 13 shown in Figure 7(b) protrudes sharply from the outer periphery toward the center toward the first side because the dead zone A is small. On the other hand, because the force with which the forging die 2 presses the titanium material 1 is relatively small, the effect of elongation due to reduction gradually decreases from the outer periphery toward the center, and the extruded portion 13 is recessed toward the second side midway. For the above reasons, inclusion occurs in the example shown in Figure 7(b).

[0053] Therefore, in order to prevent the occurrence of roll-in, it is necessary to ensure a sufficient rolling reduction length (L1-L2). As a result of repeated experiments, the inventors identified the optimal relationship between the diameter D1 of the titanium material 1, the length L1 of the forging surface 22, and the retraction length L2. Specifically, it is preferable that the length L1 of the forging surface 22 is 0.5 times or more the diameter D1 of the titanium material 1, and the retraction length L2 is 0.2 times or less. Furthermore, if the length L1 is more than three times the diameter D1, the dimension of the forging die 2 in the X direction will be too long in the X direction relative to the titanium material 1, making stable forging difficult.

[0054] The inventors also found that when the ends 10, 11 of the titanium material 1 protrude beyond the forging die 2, the occurrence of entrapment can be suppressed and a titanium material 1 with a stable shape can be formed by setting the protruding length L4 to 0.2 times or less the diameter D1 of the titanium material 1. When the titanium material 1 protrudes beyond the forging die 2, a sufficient rolling length is ensured. On the other hand, when the protruding length L4 is more than 0.2 times the diameter D1 of the titanium material 1, there is a possibility that the titanium material 1 will bend due to forging elongation, as explained above.

[0055] The titanium material forging and stretching method of the present disclosure works well when forging and stretching a relatively easily deformable high-purity titanium material with a purity of 99.9% or more excluding gas impurities. The titanium material forging and stretching method of the present disclosure also works well when the surface temperature of the titanium material 1 at the start of forging and stretching is 500°C or higher. However, if the surface temperature of the titanium material 1 at the start of forging and stretching exceeds 850°C, the composition of the titanium material 1 may change, so the surface temperature is preferably 850°C or lower.

[0056] The titanium material forging method according to this embodiment has the following advantages.

[0057] (1) A titanium material forging method for reducing the diameter of a columnar titanium material (1) extending from a first side to a second side using a forging die (2), the titanium material forging method comprising the steps of: Gripping the titanium material 1; Heating the titanium material 1; The forging of the titanium material 1 by the forging die 2 is started from the longitudinal ends 10, 11 of the titanium material 1. Equipped with.

[0058] As a result, bending of the titanium material can be suppressed compared to when the titanium material is forged from the middle position toward the end, or when the titanium material is forged from the vicinity of the part held by the manipulator toward the end, which eliminates the need for workers to shape the titanium material, thereby improving the yield of titanium material.

[0059] (2) The titanium material 1 has, among the ends 10 and 11, a first end 10 on a first side where forging and elongation are initiated and a second end 11 on a second side, The forging die 2 has a forging surface 22 on the side that contacts the titanium material 1 and a first die end portion 20 on the first side, The length L1 of the forged and stretched surface along the longitudinal direction is 0.5 to 3 times the diameter D1 of the titanium material 1, At the start of forging and stretching, the longitudinal position of the first end 10 relative to the first die end 20 is between a first position where the first end 10 retracts to the second side relative to the first die end 20 by a retraction length L2, and a second position where the first end 10 protrudes to the first side relative to the first die end 20 by a protrusion length L4, The retraction length L2 is 0.2 times or less the length L1 of the forging and stretching surface 22, The protruding length L4 is 0.2 times the diameter D1 of the titanium material 1 or less.

[0060] As a result, the extruded portion 13 formed by forging and extending the ends 10, 11 of the titanium material 1 does not have a rolled-up shape, and therefore there is no need to cut out the extruded portion 13. As a result, the yield of the titanium material can be further improved.

[0061] (3) The purity of the titanium material 1 is 99.9% or more excluding gas impurities. As a result, the titanium material forging method can function favorably.

[0062] (4) The surface temperature of the titanium material 1 at the start of forging is 500°C or higher and 850°C or lower. As a result, the titanium material forging method can function even more effectively.

[0063] The titanium material forging method according to the present disclosure is not limited to the configuration of the above embodiment, and various modifications are possible.

[0064] During the forging and stretching of the first end portion 10, the first end portion 10 of the titanium material 1 may protrude relative to the first die end portion 20, and during the forging and stretching of the second end portion 11, the second end portion 11 of the titanium material 1 may retract relative to the second die end portion 21. Conversely, during the forging and stretching of the first end portion 10, the first end portion 10 of the titanium material 1 may retract relative to the first die end portion 20, and during the forging and stretching of the second end portion 11, the second end portion 11 of the titanium material 1 may protrude relative to the second die end portion 21.

[0065] The gripping positions of the manipulator 3 do not have to be the ends 10 and 11 of the titanium material 1 .

[0066] [Note] The titanium material forging method according to the present disclosure provides the following aspects.

[0067] [Aspect 1] A titanium material forging method for reducing the diameter of a columnar titanium material extending from a first side to a second side using a forging die, the titanium material forging method comprising: gripping the titanium material; heating the titanium material; The forging of the titanium material by the forging die is started from an end portion in the longitudinal direction of the titanium material. A titanium material forging method comprising the steps of:

[0068] [Aspect 2] The titanium material has, among the end portions, a first end portion on the first side where the forging-extension starts and a second end portion on the second side, The forging die has a forging surface on a side that contacts the titanium material and a first die end portion on the first side, The length of the forged and stretched surface along the longitudinal direction is 0.5 to 3 times the diameter of the titanium material, At the start of the forging and stretching, the position of the first end in the longitudinal direction relative to the first die end is between a first position where the first end is retracted by a retracted length toward the second side relative to the first die end, and a second position where the first end protrudes by a protruding length toward the first side relative to the first die end, The retraction length is 0.2 times or less the length of the forging surface, The protruding length is 0.2 times or less the diameter of the titanium material. A method for forging a titanium material according to aspect 1.

[0069] [Aspect 3] The purity of the titanium material is 99.9% or more, excluding gas impurities; 3. The method for forging a titanium material according to claim 1 or 2.

[0070] [Aspect 4] The surface temperature of the titanium material at the start of the forging is 500°C or higher and 850°C or lower. A method for forging a titanium material according to any one of aspects 1 to 3. [Explanation of symbols]

[0071] 1: Titanium material 10:First end 11:Second end 12: Forged elongated surface 2:Forging mold 2a: Flat mold 2b: Round mold 20: First mold end 21: End of second mold 22: Forged and stretched surface 3: Manipulator L1: Length of the forged surface L2, L3: Retraction length L4, L5: protrusion length D1: Diameter of titanium material before forging D2: Diameter of titanium material after forging A: Dead Zone

Claims

1. A titanium material forging method for reducing the diameter of a columnar titanium material extending from a first side to a second side using a forging die, the titanium material forging method comprising: gripping the titanium material; heating the titanium material; The forging of the titanium material by the forging die is started from an end portion in the longitudinal direction of the titanium material. A titanium material forging method comprising the steps of:

2. The titanium material has, among the end portions, a first end portion on the first side where the forging-extension starts and a second end portion on the second side, The forging die has a forging surface on a side that contacts the titanium material and a first die end portion on the first side, The length of the forged and stretched surface along the longitudinal direction is 0.5 to 3 times the diameter of the titanium material, At the start of the forging extension, the position of the first end in the longitudinal direction relative to the first die end is between a first position where the first end is retracted by a retracted length toward the second side relative to the first die end, and a second position where the first end protrudes by a protruding length toward the first side relative to the first die end, The retraction length is 0.2 times or less the length of the forging extension surface, The protruding length is 0.2 times or less the diameter of the titanium material. The method for forging titanium material according to claim 1.

3. The purity of the titanium material is 99.9% or more, excluding gas impurities; The method for forging titanium material according to claim 1 or 2.

4. The surface temperature of the titanium material at the start of the forging is 500°C or higher and 850°C or lower. The method for forging titanium material according to claim 1 or 2.

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