A method for forging a titanium alloy drum shaft forging

Abstract

The application relates to a forging forming method of a titanium alloy drum shaft forging, belonging to the technical field of drum shaft forging production, which comprises the following steps: designing and manufacturing a sleeve with a center hole and a plug matched with the center hole; placing a tooling; placing a bar; pre-forging; finish forging; and demolding. Through the method, the production cost of the titanium alloy drum shaft forging can be reduced, and the drum shaft forging formed through finish forging is easier to demold.

Description

Technical Field

[0001] This invention belongs to the field of drum shaft forging technology, and specifically relates to a forging method for titanium alloy drum shaft forgings. Background Technology

[0002] Driven by the long-term development of high thrust-to-weight ratio aero engines, the research on high-temperature titanium alloys has always been a hot topic in the field of titanium alloy research. TC25G alloy is an (α+β) type high-temperature titanium alloy with an operating temperature of 500-550℃. It is a high-heat-strength titanium alloy developed based on the chemical composition of TC25 alloy by increasing the content of high-melting-point alloying elements such as Mo and Zr.

[0003] Journals are critical components of aero-engines, typically categorized as front journals and rear journals. Journals are rotating structures, primarily made of high-temperature alloys or high-temperature titanium alloys, such as TC17, Ti60, GH4169, GH4169G, and TC25G. Due to their higher specific strength and significant weight reduction compared to high-temperature alloys, titanium alloys have become the primary material choice for key components of advanced aero-engines, including integral bladed disks, compressor disks, blades, and rotor shafts. Journal forgings (i.e., drum shaft forgings) are formed primarily through three methods: free forging, hot die forging, and extrusion. Extrusion is a process that uses high pressure to force a metal billet through a die cavity or enclosed space, causing it to undergo plastic deformation to obtain the desired shape. Compared to traditional die forging, extrusion has a very small allowance in its design, which can reduce the blank weight by 20%-40% for the same part size. At the same time, the metal deforms under triaxial compressive stress, resulting in finer grains, fewer internal defects, and significantly better fatigue strength and impact resistance than free forging and ordinary die forging. Extrusion is highly adaptable to parts with complex cross-sections and deep hole structures, and metal flow can be controlled through positive / negative extrusion to optimize material distribution.

[0004] However, there are currently technical problems with the high cost of producing drum shaft forgings by extrusion. Specifically, firstly, because the height of the drum shaft forgings is relatively large, the cavity of the final forging die for extrusion production of drum shaft forgings needs to be designed to be relatively deep, thus requiring more material for the final forging die and increasing the die cost; secondly, the pre-forged billets obtained during the pre-forging process usually need to undergo additional machining to ensure that the billet size matches the cavity of the final forging die, otherwise the pre-forged billet may not be able to be successfully placed into the cavity of the final forging die. The machining in the above process is not only time-consuming and labor-intensive, but also increases the process cost. Summary of the Invention

[0005] This invention provides a forging method for titanium alloy drum shaft forgings, which reduces the cost of extruding drum shaft forgings.

[0006] This invention is achieved through the following technical solution: a forging method for a titanium alloy drum shaft forging, the drum shaft forging having an upper flange portion and a lower rod portion, the outer diameter of the flange portion being larger than that of the rod portion, comprising:

[0007] Tooling design: Design and manufacture a sleeve with a central hole and a plug that fits the central hole. The diameter of the central hole is adapted to the outer diameter of the rod. A positioning groove is provided on the bottom surface of the sleeve, and a frustum is provided on one side of the plug.

[0008] Place the tooling: Place the sleeve on the press worktable, making the axis of the center hole vertical, insert the plug into the center hole, and place the plug on the press worktable with the truncated cone facing upwards;

[0009] Placing the bar stock: A positioning hole is set at the center of the bottom surface of the titanium alloy bar stock. The titanium alloy bar stock is placed into the center hole, so that the frustum is inserted into the positioning hole to position the titanium alloy bar stock.

[0010] Pre-forging: Use a flat anvil to forge the titanium alloy bar to upset it into a pre-forged billet with a diameter equal to that of the bar. Then remove the pre-forged billet from the sleeve and heat it.

[0011] Final forging: Place the sleeve on the lower die of the final forging die, and use the positioning groove to position the sleeve and the lower die. Place the heated pre-forged billet into the center hole of the sleeve, and use the positioning hole to position the pre-forged billet on the lower die. The lower part of the pre-forged billet is inserted into the cavity of the lower die, and the upper part of the pre-forged billet is located above the sleeve. Then, use the upper die of the final forging die to press the upper part of the pre-forged billet downward to form the flange part, so that the pre-forged billet is formed into a drum shaft forging.

[0012] Demolding: The sleeve is locked to the upper mold using a locking pin. The upper mold is then driven to move the sleeve and the drum shaft forging upwards, so that the drum shaft forging is demolded from the lower mold. Then the locking pin is removed to separate the sleeve from the upper mold. Finally, the drum shaft forging is removed from the sleeve.

[0013] Furthermore, in order to better realize the present invention, the height of the sleeve is a, the height of the plug is b, and the height of the pre-forged billet is c, where c > ab.

[0014] Furthermore, in order to better realize the present invention, the positioning groove is located at the center of the bottom surface of the sleeve and is connected to the center hole. The center hole penetrates the top surface of the sleeve. The depth of the positioning groove is d, and the depth of the center hole is e, where a=d+e, d / e=0.25-0.34.

[0015] Furthermore, in order to better realize the present invention, the height of the drum shaft forging is f, where e / f = 0.45-0.63.

[0016] Furthermore, in order to better realize the present invention, the positioning groove is an open groove with inclined sidewalls, and the inclination angle of the sidewalls of the positioning groove is α, 30°≤α≤75°.

[0017] Furthermore, in order to better realize the present invention, the upper die of the final forging die is provided with a guide post, and the sleeve is provided with a guide hole adapted to the guide post. When the upper die presses the pre-forged billet downward during the final forging process, the guide post is inserted into the guide hole.

[0018] The outer wall of the sleeve is provided with a pin hole that communicates with the guide hole, and the guide post is provided with a locking hole that corresponds to the pin hole. When the final forging die extrudes the pre-forged billet into the drum shaft forging, the locking hole communicates with the pin hole.

[0019] One end of the locking pin passes through the pin hole and is inserted into the locking hole to lock the sleeve to the upper mold.

[0020] Furthermore, in order to better realize the present invention, the length of the locking pin is L, the total length of the locking pin inserted into the pin hole and the locking hole is s, t=Ls, and t / L≥1 / 3.

[0021] Furthermore, in order to better realize the present invention, the deformation of the bar stock during the pre-forging process is 20%-40%;

[0022] During the final forging process, the deformation of the flange is 40%, the deformation of the rod is 80%, and the deformation of the drum shaft forging gradually increases from the top to the bottom between 40% and 80%.

[0023] Furthermore, in order to better realize the present invention, the titanium alloy is designated as TC25G.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention provides a method for pre-forging a titanium alloy bar by designing and manufacturing a sleeve and a plug. During pre-forging, a titanium alloy bar is placed into the central hole of the sleeve, and then upsetting the titanium alloy bar with a flat anvil to form a pre-forged blank with a diameter equal to the rod portion of the drum shaft forging. The pre-forged blank is then removed from the sleeve and heated. The sleeve is then placed on the lower die of the final forging mold, with the central hole of the sleeve corresponding to the cavity of the lower die. The heated pre-forged blank is then placed into the sleeve, so that the lower part of the pre-forged blank passes through the sleeve and sinks into the lower die cavity, while the upper part of the pre-forged blank is positioned above the sleeve. The upper die of the final forging mold is then used to press the upper part of the pre-forged blank downwards, forming the upper part of the pre-forged blank into a flange portion, thereby forming the drum shaft forging, which is then demolded.

[0026] In both the pre-forging and final forging processes, the billet is placed in the central hole of the sleeve. This central hole restricts the billet during the pre-forging process, ensuring that the dimensions of the billet formed during pre-forging are compatible with the final forging die. This eliminates the need for additional machining to match the dimensions of the pre-forged billet to the cavity of the final forging die, thereby reducing the overall process cost and shortening the forming time. Furthermore, during the final forging process, the sleeve can be considered part of the final forging die, and the central hole of the sleeve is equivalent to part of the cavity of the final forging die. This allows the cavity of the actual final forging die to be designed and manufactured to be shallower, requiring less material to manufacture the entire final forging die, thus reducing the die cost. During the demolding process, since the formed flange is located above the sleeve, after the sleeve is connected to the upper mold using a locking pin, the sleeve will press the flange of the drum shaft forging against the bottom of the upper mold. When the upper mold moves upward, it will lift the sleeve and the formed drum shaft forging together upward, thereby demolding the drum shaft forging from the lower mold. Then, the locking pin is removed to separate the sleeve from the upper mold, and then the drum shaft forging can be removed from the sleeve. Therefore, the demolding of the drum shaft forging formed by this method is more convenient. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart of the forging method for the titanium alloy drum shaft forging provided in the embodiments of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure after the plug and sleeve are assembled in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the sleeve structure in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the plug structure in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of the pre-forged billet formed by pre-forging in an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram showing the positions of the sleeve, guide post, locking pin, and drum shaft forging during demolding in an embodiment of the present invention.

[0034] In the diagram: 100-Drum shaft forging, 110-Flange, 120-Rack, 200-Pre-forged billet, 210-Positioning hole, 300-Sleeve, 310-Center hole, 320-Positioning groove, 330-Guide hole, 400-Plug, 410-Frustum, 500-Locking pin, 600-Guide post. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example

[0036] This embodiment provides a forging method for a titanium alloy drum shaft forging 100, which has an upper flange portion 110 and a lower rod portion 120. The outer diameter of the flange portion 110 is larger than that of the rod portion 120. The titanium alloy used is grade TC25G. Figure 1 As shown, the method includes the following steps:

[0037] Step 1: Tooling Design. Design and manufacture a sleeve 300 with a center hole 310 (e.g., Figure 3 (as shown) and a plug 400 adapted to the center hole 310 (as shown) Figure 4 As shown), the central hole 310 is a straight hole that penetrates the top surface of the sleeve 300. The diameter of the central hole 310 is adapted to the outer diameter of the rod 120. A positioning groove 320 is provided on the bottom surface of the sleeve 300. The positioning groove 320 is connected to the central hole 310. A frustum 410 is provided on one side of the plug 400.

[0038] Step 2: Place the tooling. Place the sleeve 300 on the press worktable, ensuring the axis of the center hole 310 is vertical. Insert the plug 400 into the center hole 310, positioning the plug 400 on the press worktable with the frustum 410 facing upwards. At this point, the plug 400 is located within the aforementioned center hole 310, specifically as follows: Figure 2 As shown. In fact, the frustum 410 is the same as the positioning structure in the cavity of the lower die of the final forging die used to position the pre-forged billet 200.

[0039] Step 3: Placing the bar stock. A positioning hole 210 is pre-set at the center of the bottom surface of the titanium alloy bar stock, which is adapted to the aforementioned frustum 410. The titanium alloy bar stock is placed into the center hole 310, allowing the frustum 410 to be inserted into the positioning hole 210 and thus positioning the titanium alloy bar stock. It is worth noting that the diameter of the titanium alloy bar stock is smaller than the diameter of the center hole 310, and the frustum 410 is located at the center of the plug 400. This positions the bar stock at the center of the center hole 310, creating a gap between the outer wall of the bar stock and the wall of the center hole 310.

[0040] Step 4: Pre-forging. The titanium alloy bar is forged using a flat anvil facing down, upsetting it into a pre-forged blank 200 with a diameter equal to the rod portion 120. The pre-forged blank 200 is then removed from the sleeve 300 and heated. During this process, due to the limitation of the central hole 310 wall, the titanium alloy bar can only be upset to a pre-forged blank 200 with a diameter equal to the central hole 310 diameter. However, to facilitate the removal of the pre-forged blank 200, the central hole 310 diameter is designed to be slightly larger than the diameter of the rod portion 120 of the drum shaft forging 100. Therefore, the actual diameter of the pre-forged blank 200 is slightly smaller than the central hole 310 diameter, as shown below. Figure 5 As shown.

[0041] Step 5: Final Forging. Place the sleeve 300 on the lower die of the final forging mold. It is worth noting that at this time, the plug 400 is not in the center hole 310 of the sleeve 300. The positioning groove 320 is used to position the sleeve 300 and the lower die. Specifically, the upper part of the lower die of the final forging mold is provided with a positioning step that matches the positioning groove 320. When the sleeve 300 is placed on the lower die, the positioning groove 320 is upside down on the positioning step of the lower die, and the center hole 310 of the sleeve 300 matches and corresponds to the cavity of the lower die. At this time, the sleeve 300 becomes part of the lower die, and the center hole 310 becomes part of the cavity of the lower die. The heated pre-forged billet 200 is placed into the central hole 310 of the sleeve 300. The positioning hole 210 positions the pre-forged billet 200 on the lower die. It should be noted that the bottom of the cavity of the lower die is provided with a positioning structure similar to the aforementioned frustum 410. When the pre-forged billet 200 is inserted, the positioning hole 210 at the bottom of the pre-forged billet 200 is upside down and positioned on the positioning structure. At this time, the lower part of the pre-forged billet 200 is inserted into the cavity of the lower die, and the upper part of the pre-forged billet 200 is located above the sleeve 300. Then, the upper part of the pre-forged billet 200 is pressed downward by the upper die of the final forging die to form the aforementioned flange portion 110. The flange portion 110 is located above the sleeve 300. At this time, the portion placed in the central hole 310 of the sleeve 300 and the cavity of the lower die forms the aforementioned rod portion 120, so that the pre-forged billet 200 is formed into a drum shaft forging 100.

[0042] The top surface of the sleeve 300 can be a plane or a stepped hole surface that fits the lower mold cavity.

[0043] Demolding: Use locking pin 500 to lock sleeve 300 to the upper mold, as detailed below. Figure 6 As shown, the upper die is driven to move the sleeve 300 and the drum shaft forging 100 upwards, so that the drum shaft forging 100 is demolded from the lower die. Then, the locking pin 500 is removed to separate the sleeve 300 from the upper die. Finally, the drum shaft forging 100 is removed from the sleeve 300.

[0044] An optional implementation of this embodiment is as follows: the height of the sleeve 300 is defined as a, the height of the plug 400 is defined as b, and the height of the pre-forged billet 200 is defined as c, where c > ab, that is, the height of the pre-forged billet 200 is greater than the depth of the central hole 310.

[0045] The aforementioned positioning groove 320 is located at the center of the bottom surface of the sleeve 300 and communicates with the center hole 310, which penetrates the top surface of the sleeve 300. The depth of the positioning groove 320 is defined as 'd', and the depth of the center hole 310 is defined as 'e', ​​where a = d + e, and d / e = 0.25-0.34. It should be noted that if the ratio is less than 0.25, the sleeve 300 will deviate during final forging, affecting the concentricity of the forging and posing a safety hazard. If the ratio exceeds 0.34, it will lengthen the height of the sleeve 300, increasing the manufacturing cost of the plug 400 and the ejector pin, which does not meet the requirements of lean manufacturing. Specifically, d / e = 0.25, d / e = 0.29, or d / e = 0.34, etc.

[0046] The height of the drum shaft forging 100 is defined as f, where e / f = 0.45-0.63. That is, the height of the drum shaft forging 100 is greater than the depth of the central hole 310. After the pre-forged billet 200 is placed into the central hole 310, the lower part of the pre-forged billet 200 passes through the central hole 310 and the positioning groove 320 before entering the lower mold cavity, while the upper part of the pre-forged billet 200 remains above the sleeve 300. It should be noted that when the ratio is greater than 0.63, the pre-forged billet 200, due to its excessively high effective height, will have an excessively long flow path along the die neck during the forward extrusion process, leading to significant tearing at the neck of the forging and affecting surface quality. When the ratio is less than 0.45, the pre-forged billet 200, due to its excessively large diameter, will have an excessively long flow path along the die head during the forward extrusion process, resulting in tearing at the transition between the head and neck, affecting the strength and surface quality of the forging. Specifically, e / f = 0.45, e / f = 0.52, or e / f = 0.63, etc.

[0047] The aforementioned positioning groove 320 is an open groove with inclined sidewalls, and the inclination angle of the sidewalls of the positioning groove 320 is α, where 30°≤α≤75°, that is, the value of α is between 30° and 75°. It should be noted that when the depth of the positioning groove 320 is constant, if the angle α is less than 30°, the edge thickness of the positioning strip will be too small, posing a safety hazard of mold cracking during pressing; if the angle α is greater than 75°, the slope of the positioning strip will be too steep, which is not conducive to the assembly of the final mold, and will also excessively extend the height of the sleeve 300, lacking economic efficiency. Specifically, the value of α can be 30°, 45°, 60°, or 75°, etc.

[0048] An optional implementation of this embodiment is as follows: The upper die of the final forging die is provided with a guide post 600, and the top surface of the sleeve 300 is provided with a guide hole 330 adapted to the guide post 600. When the upper die presses the pre-forged billet 200 downward during the final forging process, the guide post 600 is inserted into the guide hole 330, thereby guiding the vertical movement of the upper die. A pin hole communicating with the guide hole 330 is provided on the outer wall of the sleeve 300, and a locking hole corresponding to the pin hole is provided on the guide post 600. When the final forging die extrudes the pre-forged billet 200 into a drum shaft forging 100, the locking hole and the pin hole are connected. When it is necessary to lock the sleeve 300 and the upper die together, one end of the locking pin 500 passes through the pin hole and is inserted into the locking hole. During the final forging process, the upper die needs to move vertically relative to the lower die and the sleeve 300. At this time, the locking pin 500 is not inserted into the locking hole and the pin hole. When demolding is required, the locking pin 500 is then inserted into the locking hole and the pin hole.

[0049] Let L be the length of the locking pin 500, and s be the total length of the locking pin 500 inserted into the pin hole and the lock hole. Let t = Ls, meaning the length of the portion of the locking pin 500 remaining outside the sleeve 300 is t. t / L ≥ 1 / 3. For example, t = 1 / 3L or t = 1 / 2L, etc.

[0050] An optional implementation of this embodiment is as follows: During the pre-forging process, the deformation of the bar stock is 20%-40%, for example, 20%, 30%, or 40%. During the final forging process, the deformation of the flange portion 110 is 40%, and the deformation of the rod portion 120 is 80%. Furthermore, the deformation of the drum shaft forging 100 gradually increases from the top to the bottom, but the value of the deformation ranges between 40% and 80%.

[0051] By coordinating the deformation during the pre-forging and final forging processes, the deformation of the drum shaft forging 100 in each region during the forming process can be made more uniform, and the probability of surface tensile cracks in the forging can be reduced to a certain extent.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A forging method for a titanium alloy drum shaft forging, the drum shaft forging (100) having an upper flange portion (110) and a lower rod portion (120), the outer diameter of the flange portion (110) being larger than that of the rod portion (120), characterized in that, include: Tooling design: Design and manufacture a sleeve (300) with a center hole (310) and a plug (400) adapted to the center hole (310). The diameter of the center hole (310) is adapted to the outer diameter of the rod (120). A positioning groove (320) is provided on the bottom surface of the sleeve (300), and a frustum (410) is provided on one side of the plug (400). Place the tooling: Place the sleeve (300) on the press worktable, make the axis of the center hole (310) vertical, put the plug (400) into the center hole (310), and place the plug (400) on the press worktable with the frustum (410) facing upward; Placing the bar: A positioning hole (210) is set at the center of the bottom surface of the titanium alloy bar. The titanium alloy bar is placed into the center hole (310) so that the frustum (410) is inserted into the positioning hole (210) to position the titanium alloy bar. Pre-forging: The titanium alloy bar is forged with a flat anvil facing down to upset the titanium alloy bar into a pre-forged billet (200) with a diameter equal to that of the bar (120). The pre-forged billet (200) is then removed from the sleeve (300) and heated. Final forging: The sleeve (300) is placed on the lower die of the final forging die. The positioning groove (320) is used to position the sleeve (300) and the lower die. The heated pre-forged billet (200) is placed into the center hole (310) of the sleeve (300). The positioning hole (210) is used to position the pre-forged billet (200) on the lower die. The lower part of the pre-forged billet (200) is inserted into the cavity of the lower die. The upper part of the pre-forged billet (200) is located above the sleeve (300). Then, the upper part of the pre-forged billet (200) is pressed downward by the upper die of the final forging die to form the flange part (110), so that the pre-forged billet (200) is formed into a drum shaft forging (100). Demolding: Use the locking pin (500) to lock the sleeve (300) to the upper mold, drive the upper mold to move the sleeve (300) and the drum shaft forging (100) upward, so that the drum shaft forging (100) is demolded from the lower mold. Then remove the locking pin (500) to separate the sleeve (300) from the upper mold. Finally, remove the drum shaft forging (100) from the sleeve (300).

2. The forging method for the titanium alloy drum shaft forging according to claim 1, characterized in that: The height of the sleeve (300) is a, the height of the plug (400) is b, and the height of the pre-forged billet (200) is c, where c > ab.

3. The forging method for the titanium alloy drum shaft forging according to claim 2, characterized in that: The positioning groove (320) is located at the center of the bottom surface of the sleeve (300) and communicates with the center hole (310). The center hole (310) penetrates the top surface of the sleeve (300). The depth of the positioning groove (320) is d, and the depth of the center hole (310) is e, where a=d+e, d / e=0.25-0.

34.

4. The forging method for the titanium alloy drum shaft forging according to claim 3, characterized in that: The height of the drum shaft forging (100) is f, where e / f = 0.45-0.

63.

5. The forging method for the titanium alloy drum shaft forging according to claim 3, characterized in that: The positioning groove (320) is an open groove with inclined sidewalls, and the inclination angle of the sidewalls of the positioning groove (320) is α, 30°≤α≤75°.

6. The forging method for the titanium alloy drum shaft forging according to claim 1, characterized in that: The upper die of the final forging die is provided with a guide post (600), and the sleeve (300) is provided with a guide hole (330) adapted to the guide post (600). When the upper die presses the pre-forged billet (200) downward during the final forging process, the guide post (600) is inserted into the guide hole (330). The outer wall of the sleeve (300) is provided with a pin hole that communicates with the guide hole (330), and the guide post (600) is provided with a locking hole corresponding to the pin hole. When the final forging die extrudes the pre-forged billet (200) into the drum shaft forging (100), the locking hole communicates with the pin hole. One end of the locking pin (500) passes through the pin hole and is inserted into the locking hole to lock the sleeve (300) together with the upper mold.

7. The forging method for the titanium alloy drum shaft forging according to claim 6, characterized in that: The length of the locking pin (500) is L, the total length of the locking pin (500) inserted into the pin hole and the lock hole is s, t=Ls, and t / L≥1 / 3.

8. The forging method for the titanium alloy drum shaft forging according to claim 1, characterized in that: During the pre-forging process, the deformation of the bar stock is 20%-40%; During the final forging process, the deformation of the flange (110) is 40%, the deformation of the rod (120) is 80%, and the deformation of the drum shaft forging (100) gradually increases from the top to the bottom between 40% and 80%.

9. The forging method for the titanium alloy drum shaft forging according to claim 1, characterized in that: The titanium alloy is designated as TC25G.

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