Forging forming method of small hole large axis ratio hollow flange part of TC17 titanium alloy

Abstract

The present application provides a kind of TC17 titanium alloy small hole big axial ratio hollow flange part forging forming method, which can make material fill the lower end of the shaft part of the forging, and the final forging deformation of the forging reaches more than 20%.The TC17 titanium alloy small hole big axial ratio hollow flange part forging forming method includes designing a final forging according to the hollow flange part, designing a final forging die and a pre-forging blank according to the final forging, and the pre-forging blank includes a disc part and a solid vertical rod connected to one end of the disc part to form a T-shaped structure in longitudinal section, wherein the diameter d of the vertical rod is d≤D-40mm, D is the diameter of the first cavity section, the side surface of the disc part is an arc surface with a raised middle, the lower end of the side surface cooperates with the inner wall of the second forming cavity section, and the maximum outer diameter of the side surface does not exceed the opening diameter of the second forming cavity section.The final forging (part) formed by the method of the present application has a final forging deformation of more than 20% at each location, meeting the requirements.

Description

Technical Field

[0001] This invention relates to the field of die forging technology, specifically a forging method for a TC17 titanium alloy hollow flange part with a small hole and a large shaft diameter ratio. Background Technology

[0002] TC17 titanium alloy is a near-β titanium alloy rich in β-stabilizing elements, with a nominal composition of (% by mass) Ti-5Al-2Sn-2Zr-4Mo-4Cr. TC17 titanium alloy has high strength, good fracture toughness and fatigue performance, and can achieve good matching, thus possessing excellent comprehensive mechanical properties. It is widely used in components such as high-pressure compressor disks and fan disks of turbofan aero engines.

[0003] Currently, TC17 forgings are formed using β hot die forging, and a basketweave structure should be formed after forging and heat treatment. To meet the performance requirements of some special applications, all original β grain boundaries in TC17 forgings must be broken, and coarse, straight, continuous α grain boundaries are not allowed. This requires that the deformation of the part body should reach more than 20% when using β hot die forging for TC17 forgings.

[0004] like Figure 1 As shown, the hollow flange part 1 generally consists of an annular body 11, a shaft portion 13, and a frustoconical transition section 12 disposed between the annular body 11 and the shaft portion 13. For the TC17 titanium alloy flange part 1 with a shaft diameter ratio L / D of 3 or higher and a central hole diameter of less than 150 mm, it is a product that is difficult to form and control. Traditional forging production methods such as billet preparation + die forging or direct bar die forging are difficult to guarantee the required deformation amount of the final forged part, resulting in the failure to obtain a basket-like structure. On the other hand, with a shaft diameter ratio of 3.0 or higher, it is difficult to fill the lower end of the shaft portion during die forging. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a forging method for TC17 titanium alloy hollow flange parts with small holes and large shaft diameter ratio, in which the material can easily fill the lower end of the shaft portion of the forging and the final forging deformation of the forging reaches more than 20%.

[0006] The technical solution adopted by this invention to solve its technical problem is: a forging method for a TC17 titanium alloy hollow flange part with a small hole and a large shaft diameter ratio, wherein the hollow flange part includes a hollow annular body, a shaft portion, and a frustoconical transition section disposed between the annular body and the shaft portion, and the forging method for the hollow flange part includes the following steps:

[0007] According to the design of the hollow flange part, the final forging of the final forging has a Y-shaped longitudinal section, including an annular final forging part designed according to the annular body, a frustum-shaped transition section final forging part designed according to the frustum-shaped transition section, and a solid rod part designed according to the shaft part.

[0008] The final forging die and pre-forging blank are designed according to the final forging part. The final forging die includes an upper die and a lower die that cooperates with the upper die. The lower die has a first cavity section for forming the solid rod part and a second truncated cone-shaped forming cavity section for forming the truncated cone-shaped transition section final forging part. The upper die is provided with a boss for forming the truncated cone-shaped transition section final forging part and the inner cavity of the annular body final forging part, and also has an upper cavity for forming the annular body final forging part. The pre-forging blank includes a disc part and a solid upright rod with one end connected to the disc part to form a T-shaped structure in longitudinal section. The diameter d of the upright rod is d≤D-40mm, where D is the diameter of the first cavity section. The side of the disc part is an arc-shaped surface with a central convex shape. The lower end of the side part cooperates with the inner wall of the second forming cavity section. The maximum outer diameter of the side part does not exceed the opening diameter of the second forming cavity section.

[0009] Form the pre-forged billet;

[0010] The pre-forged billet is placed in the final forging mold to form the final forging. During the final forging, the pre-forged billet is positioned by the lower side of the disc portion of the pre-forged billet engaging with the inner wall of the second forming cavity to prevent the pre-forged billet from shifting.

[0011] The final forging is processed to remove excess material to obtain the hollow flange part.

[0012] Furthermore, the maximum outer diameter of the side is equal to the opening diameter of the second cavity segment.

[0013] Furthermore, the upper surface of the disk portion is convex at the center.

[0014] Furthermore, the upward tilt angle α of the center of the upper surface of the disk portion is greater than or equal to 5°.

[0015] Furthermore, a positioning groove is provided at the center of the lower end face of the upright, and a positioning platform that mates with the positioning groove is provided at the bottom of the first cavity section.

[0016] The beneficial effects of this invention are as follows: The forging method for the TC17 titanium alloy hollow flange part with a small hole and a large shaft diameter ratio can not only position the pre-forged billet 4 by cooperating with the lower side of the disc portion 41 of the pre-forged billet 4 with the inner wall of the second forming cavity section 322 during the final forging process, preventing the pre-forged billet 4 from shifting, but also facilitate the material of the upper part of the disc portion to flow downward along the lower mold cavity, so that the material can fill the cavity of the lower mold, which is convenient for the final forging and shape control; and the diameter d of the upright 42 is less than or equal to the diameter of the first cavity section 321 minus 40mm, that is, there is at least 40mm between the upright 42 and the inner wall of the first cavity section 321, so that the upright 42 has a sufficiently large deformation space, ensuring that the material of the lower solid upright 42 can undergo a sufficiently large deformation when the boss 311 is forming the inner cavity of the annular body 11 and the shaft portion 13. Through simulation, the forging (part) formed by the method of this invention has a final forging deformation of more than 20% at all points, which meets the requirements, and the method is simple. Attached Figure Description

[0017] Figure 1 This is a half-section structural diagram of hollow flange part 1;

[0018] Figure 2 This is a schematic diagram of the structure of the final forging of the present invention;

[0019] Figure 3 This is a schematic diagram of the final forging die of the present invention;

[0020] Figure 4 This is a schematic diagram of the pre-forged billet structure of the present invention;

[0021] Figure 5 This is a schematic diagram of the final forging of the pre-forged billet according to the present invention;

[0022] Figure 6 This is a distribution diagram of the material deformation at the part position of the final forging formed by the method of the present invention in Example 1;

[0023] Figure 7 This is a distribution diagram of the material deformation at the part position of the final forging formed by the method of the present invention in Example 2;

[0024] The figure shows: hollow flange part 1, design final forging part 2, design final forging die 3, pre-forging billet 4, annular body 11, frustum-shaped transition section 12, shaft part 13, annular body final forging part 21, frustum-shaped transition section final forging part 22, solid rod part 23, upper die 31, lower die 32, disc part 41, upright 42, boss 311, upper cavity 312, first cavity section 321, second forming cavity section 322, positioning table 323, positioning groove 421. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 As shown, the forging method of the TC17 titanium alloy hollow flange part with a small hole and a large shaft diameter ratio of the present invention includes a hollow flange part 1 comprising a hollow annular body 11, a shaft portion 13, and a frustoconical transition section 12 disposed between the annular body 11 and the shaft portion 13. The forging method of the hollow flange part 1 includes the following steps:

[0027] Step 1, such as Figure 2 As shown, the final forging part 2 is designed according to the shape and size of the hollow flange part 1. The longitudinal section (the section cut along the axis of the final forging part) of the final forging part 2 is a Y-shaped structure, including an annular final forging part 21 designed according to the annular body 11, a frustum-shaped transition section final forging part 22 designed according to the frustum-shaped transition section 12, and a solid rod part 23 designed according to the shaft part 13.

[0028] Step Two, as follows Figure 3 and Figure 4 As shown, the final forging die 3 and the pre-forging billet 4 are designed according to the shape and size of the final forging part 2. The final forging die 3 includes an upper die 31 and a lower die 32 that cooperates with the upper die 31. The lower die 32 has a first cavity section 321 for forming the solid rod part 23 and a frustum-shaped second forming cavity section 322 for forming the frustum-shaped transition section final forging part 22. The upper die 31 is provided with a boss 311 for forming the frustum-shaped transition section final forging part 22 and the inner cavity of the annular final forging part 21, and is also provided for forming the annular final forging part. The upper cavity 312 of 21; the pre-forged billet 4 includes a disc portion 41 and a solid upright 42 connected at one end to the disc portion 41 to form a T-shaped structure in longitudinal section, wherein the diameter d of the upright 42 is ≤ D-40mm, D is the diameter of the first cavity section 321, the side of the disc portion 41 is an arc-shaped surface with a central protrusion, the lower end of the side is engaged with the inner wall of the second forming cavity section 322, and the maximum outer diameter C of the side does not exceed the opening diameter of the second forming cavity section 322;

[0029] Step 3: Form the pre-forged billet 4, which can be formed by die forging;

[0030] Step 4, as follows Figure 5 As shown, the pre-forged billet 4 is placed in the final forging mold 3 for forging until the material fills the upper and lower mold cavities, thereby forming the final forging 2. During the final forging, the lower side of the disc portion 41 of the pre-forged billet 4 is positioned by cooperating with the inner wall of the second forming cavity section 322 to prevent the pre-forged billet 4 from shifting during the final forging.

[0031] Step 5: Machining the final forging 2 to remove excess material to obtain the hollow flange part 1.

[0032] When designing the final forging part 2, a certain machining allowance can be designed as needed.

[0033] The forging method for TC17 titanium alloy hollow flange parts with small holes and large shaft diameter ratio of the present invention uses a pre-forged billet with a T-shaped longitudinal section to form a final forging with a solid rod and a Y-shaped longitudinal section. Finally, the inner cavity of the shaft part of the part is formed by removing the excess material inside the solid rod part of the final forging by machining, which makes the forming of hollow flange parts with small holes and large shaft diameter ratio of the present invention more convenient. The method of the present invention designs the final forging 2 as a Y-shaped structure consisting of an annular final forging part 21 designed according to the annular body 11, a frustum-shaped transition section final forging part 22 designed according to the frustum-shaped transition section 12, and a solid rod part 23 designed according to the shaft part 13. The pre-forging billet 4 is designed as a solid upright 42 with a T-shaped longitudinal section formed by connecting the disc parts 41. The diameter d of the upright 42 is less than or equal to the diameter of the first cavity section 321 minus 40 mm. The side of the disc part 41 is an arc-shaped surface with a central convexity. The lower end of the side part 41 mates with the inner wall of the second forming cavity section 322. The maximum outer diameter of the side part 41 does not exceed the opening diameter of the second forming cavity section 322. The forging is not formed during final forging. The shaft cavity allows for positioning during the final forging process. This is achieved by the lower side of the disc portion 41 of the pre-forged billet 4 engaging with the inner wall of the second forming cavity section 322, preventing the pre-forged billet 4 from shifting. It also facilitates the downward flow of material from the upper part of the disc portion along the lower mold cavity, ensuring the material fills the lower mold cavity and facilitating the final forging. The diameter d of the upright 42 is less than or equal to the diameter of the first cavity section 321 minus 40mm. This means there is at least a 40mm gap on one side between the upright 42 and the inner wall of the first cavity section 321, providing sufficient deformation space for the upright 42. This ensures that the boss 311 can deform sufficiently when forming the inner cavity of the annular body 11 and the shaft portion 13. Simulations show that the final forging deformation of the flange parts formed using the method of this invention reaches over 30% at all points, meeting the requirements and solving the problems of difficult forming and shape control for small-hole flange parts with a shaft-to-diameter ratio of 3 or higher.

[0034] In this invention, preferably, the maximum outer diameter C of the side is equal to the opening diameter of the second forming cavity segment 322, so as to facilitate the flow of material into the downward mold cavity and the upward mold cavity 312.

[0035] like Figure 4 As shown, in order to further increase the deformation of the material in the upright part of the initial billet during final forging, the upper surface of the disc part 41 of the present invention is convex at the center.

[0036] Through simulation, it was found that when the upward tilt angle α of the upper surface center of the disc portion 41 is greater than or equal to 5°, the deformation effect on the material of the initial blank upright part during forging is better for parts with a final shaft diameter ratio greater than 3. Theoretically, the larger the shaft diameter ratio of the hollow flange part 1, the larger the upward tilt angle α of the upper surface center of the disc portion 41 of its pre-forged blank should also be.

[0037] like Figure 3 and Figure 4 As shown in this embodiment of the invention, a positioning groove 421 is provided at the center of the lower end face of the upright 42, and a positioning platform 323 that mates with the positioning groove 421 is provided at the bottom of the first cavity section 321. Thus, during final forging, the lower end of the upright 42 can be positioned by the positioning platform 323 engaging with the positioning groove 421, which is more conducive to ensuring uniform deformation of the final forging material, especially the solid rod material, and more conducive to ensuring that the deformation of each part of the final forging meets the requirements.

[0038] Example 1: The shaft diameter ratio of hollow flange part 1 is 3.5, and the inner diameter of the shaft is 124mm;

[0039] Step 1: Forge the final part 2 according to the design of the hollow flange part 1;

[0040] Step 2: Design the final forging mold 3 and the pre-forging billet 4 according to the final forging part 2. The diameter d of the upright 42 is d = D - 40mm. The side of the disc part 41 is an arc-shaped surface with a raised center. The lower end of the side is fitted with the inner wall of the second forming cavity section 322. The maximum outer diameter of the side is equal to the opening diameter of the second forming cavity section 322. The upward tilt angle α of the center of the upper surface of the disc part 41 is equal to 5°.

[0041] Step 4: Form the pre-forged billet 4;

[0042] Step 5: Place the pre-forged billet 4 in the final forging die 3 to form the final forging 2;

[0043] Step 6: Process the final forging 2 to remove excess material to obtain the hollow flange part 1;

[0044] Figure 6 This is a deformation distribution diagram of the part material location of the final forging 2. It can be seen from the diagram that the minimum deformation of each part of the final forging is 0.272 and the maximum is 1.5. According to the table of deformation and true strain correspondence, the deformation of the forging reaches more than 20%, and most of them reach more than 30%.

[0045] Example 2: The shaft diameter ratio of hollow flange part 1 is 3.5, and the inner diameter of the shaft is 124mm;

[0046] Step 1: Forge the final part 2 according to the design of the hollow flange part 1;

[0047] Step 2: Design the final forging mold 3 and the pre-forging billet 4 according to the final forging part 2. The diameter d of the upright 42 is d = D - 50mm. The side of the disc part 41 is an arc-shaped surface with a raised center. The lower end of the side is fitted with the inner wall of the second forming cavity section 322. The maximum outer diameter of the side is equal to the opening diameter of the second forming cavity section 322. The upward tilt angle α of the center of the upper surface of the disc part 41 is equal to 7°.

[0048] Step 4: Form the pre-forged billet 4;

[0049] Step 5: Place the pre-forged billet 4 in the final forging die 3 to form the final forging 2;

[0050] Step 6: Process the final forging 2 to remove excess material to obtain the hollow flange part 1;

[0051] Figure 7 This is a deformation distribution diagram of the part material location of the final forging 2 mentioned above. It can be seen from the diagram that the minimum deformation of each part of the final forging is 0.254 and the maximum is 1.86. According to the table of deformation and true strain correspondence, the deformation of the forging reaches more than 20%, and most of them reach more than 30%.

Claims

1. A forging method for a TC17 titanium alloy hollow flange part with a small bore and large shaft diameter ratio, wherein the hollow flange part (1) comprises a hollow annular body (11), a shaft portion (13), and a frustum-shaped transition section (12) disposed between the annular body (11) and the shaft portion (13), characterized in that, The forging method for the hollow flange part (1) includes the following steps: According to the design of the hollow flange part (1), the final forging part (2) has a Y-shaped longitudinal section, including an annular body final forging part (21) designed according to the annular body (11), a frustum-shaped transition section final forging part (22) designed according to the frustum-shaped transition section (12), and a solid rod part (23) designed according to the shaft part (13); Design the final forging die (3) and the pre-forging billet (4) according to the final forging part (2). The final forging die (3) includes an upper die (31) and a lower die (32) that cooperates with the upper die (31). The lower die (32) has a first cavity section (321) for forming the solid rod part (23) and a second frustum-shaped forming cavity section (322) for forming the frustum-shaped transition section final forging part (22). The upper die (31) is provided with a boss (311) for forming the frustum-shaped transition section final forging part (22) and the inner cavity of the annular final forging part (21), and is also provided with a forming annular final forging part. The upper cavity (312) of the part (21); the pre-forged billet (4) includes a disc part (41) and a solid upright (42) with one end connected to the disc part (41) to form a T-shaped structure in longitudinal section, wherein the diameter d of the upright (42) is ≤ D-40mm, D is the diameter of the first cavity section (321), the side of the disc part (41) is an arc-shaped surface with a raised middle, the lower end of the side is engaged with the inner wall of the second forming cavity section (322), and the maximum outer diameter of the side does not exceed the opening diameter of the second forming cavity section (322); Forming the pre-forged billet (4); The pre-forged billet (4) is placed in the final forging mold (3) to form the final forging (2). During the final forging, the pre-forged billet (4) is positioned by the lower end of the side of the disc portion (41) of the pre-forged billet (4) cooperating with the inner wall of the second forming cavity (322) to prevent the pre-forged billet (4) from shifting. The final forging (2) is machined to remove excess material to obtain the hollow flange part (1).

2. The forging method for the TC17 titanium alloy small-hole, large-diameter-ratio hollow flange part as described in claim 1, characterized in that, The maximum outer diameter of the side is equal to the opening diameter of the second forming cavity segment (322).

3. The forging method for the TC17 titanium alloy small-hole, large-diameter-ratio hollow flange part as described in claim 1, characterized in that, The upper surface of the disk portion (41) is convex at the center.

4. The forging method for the TC17 titanium alloy small-hole, large-diameter-ratio hollow flange part as described in claim 3, characterized in that, The upper surface of the disk portion (41) has an upward tilt angle α greater than or equal to 5°.

5. The forging method for the TC17 titanium alloy small-hole, large-diameter-ratio hollow flange part as described in claim 1, characterized in that, The lower end face of the upright (42) is provided with a positioning groove (421), and the bottom of the first cavity section (321) is provided with a positioning platform (323) that cooperates with the positioning groove (421).

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