Controllable strain isothermal forging die and method for double-structured titanium alloy bladed disk

Abstract

This invention discloses a controllable strain isothermal forging die and method for a dual-structure titanium alloy bladed disk. The forming die includes a bladed disk preform, an upper die, a lower die, and several sets of punches. Each set of punches includes an upper punch and a lower punch. The upper die and the lower die are provided with forming grooves. The forming method utilizes two forming grooves, the upper punch, and the lower punch to form a forming cavity for placing the bladed disk preform. The bladed disk preform in the forming cavity is formed by controllable strain isothermal forging to obtain the formed bladed disk. This method can achieve a gradient dual-structure / dual-performance distribution in the formed bladed disk, with equiaxed structure in the disk part, basket structure in the blade part, and gradually transitioned structure along the diameter direction in the connecting part, thereby improving the service performance and service life of the bladed disk parts.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy materials technology, and in particular to a controllable strain isothermal forging die and method for a double-structured titanium alloy bladed disk. Background Technology

[0002] The problem of achieving both blade and disk performance in conventional homogeneous / single-performance titanium alloy integral bladed disks is very prominent. The dual-structure distribution of the bladed disk, which forms an equiaxed structure in the disk area, a basket weave structure in the blade area, and a gradually transitioning structure along the diameter direction in the connecting area, is an ideal way to solve the problem of achieving both blade and disk performance.

[0003] Isothermal forging includes conventional isothermal forging and controlled strain isothermal forging (which can be achieved through a combination of multiple dies). It is a forming method that achieves plastic forming of parts by the isothermal thermoplastic flow of metal within a die. In controlled strain isothermal forging, the controlled strain deformation of the disk portion of the preform precast by the punch allows for effective deformation of the disk portion, while the blade portion does not undergo effective deformation, and the connecting portion undergoes gradual deformation along the diameter direction. This results in the complete α+β basket structure in the disk portion, no spheroidization in the blade portion, and gradual spheroidization along the diameter direction in the connecting portion. This achieves a gradient dual-structure distribution of equiaxed structure in the disk portion, basket structure in the blade portion, and gradually transitioning structure along the diameter direction in the connecting portion, providing a new method for the development of dual-structure titanium alloy bladed disks. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems existing in the prior art and to provide a controllable strain isothermal forging die and method for a double-structured titanium alloy bladed disk.

[0005] To achieve the above objectives, the technical solution provided by the present invention is: a controllable strain isothermal forging die for a double-structured titanium alloy bladed disk, the forming die comprising a bladed disk preform, an upper die, a lower die, and several sets of punches, each set of punches comprising an upper punch and a lower punch; both the upper die and the lower die are provided with forming grooves; the two forming grooves, the upper punch, and the lower punch are fastened together to form a forming cavity for placing the bladed disk preform, and the bladed disk preform in the forming cavity is formed into a bladed disk after controllable strain isothermal forging;

[0006] The formed bladed disk includes a connecting part, a disk part, and a blade part. The thickness of the disk part is smaller than that of the blade part and the connecting part. The shapes of the connecting part, the blade part, and the disk part are gradually transitioned. The upper punch and the lower punch are respectively provided with an upper punch gradient transition area and a lower punch gradient transition area. The width of the upper punch gradient transition area and the lower punch gradient transition area corresponds to the gradient width of the connecting part and the blade part, which is used to control the shape of the disk part, the connecting part, and the blade part of the formed bladed disk.

[0007] Preferably, the bladed disk preform includes a preformed disk portion and a preformed blade portion. The shape of the bladed disk preform is a disc-shaped protrusion in the middle of the preformed disk portion. The thickness and diameter length of the preformed blade portion are equal to the thickness and diameter length of the blade portion, respectively.

[0008] Preferably, the microstructure of the preform wheel disk region and the preform blade region is a basket webbing structure.

[0009] Preferably, the upper punch with an upper punch gradient transition zone and the lower punch with a lower punch gradient transition zone are driven by an external hydraulic device and extruded into the forming cavity through the through holes on the upper and lower dies for controlled strain isothermal forging of the bladed disk preform.

[0010] Preferably, the forming groove and the shapes of the upper and lower dies are symmetrical. The upper and lower dies are respectively provided with through holes that move in conjunction with the upper and lower punches. The through holes are connected to the forming cavity and the outside. The diameter of the through holes is equal to the diameter of the upper and lower punches.

[0011] This invention also discloses a forming method for a controllable strain isothermal forging die for a double-structured titanium alloy bladed disk, the forming method comprising the following steps:

[0012] S1: Titanium alloy is pre-forged into bladed disk preforms using a near-β forging method. The preform disk portion of the bladed disk preform has different initial heights, and the preform disk portion and the preform blade portion of the bladed disk preform have a basket structure inside.

[0013] S2: The pre-forged bladed disk preform in S1 is fastened into the forming cavity formed by the fastening of two forming grooves, the upper punch and the lower punch, and then subjected to controlled strain isothermal die forging.

[0014] S3: Driven by an external hydraulic device, the upper and lower punches are extruded into the forming cavity through the through holes on the upper and lower dies. At a specific temperature, the upper and lower punches are isothermally extruded at the same extrusion rate to the preform disc portion to the preset thickness. During the die forging process, the basket structure of the preform disc portion is completely spheroidized to form an equiaxed structure, while the preform blade portion does not undergo spheroidization and retains the basket structure. The connection between the preform disc portion and the preform blade portion undergoes gradual spheroidization along the diameter direction to form a gradual transition structure, ultimately resulting in the formed bladed disk. The equiaxed structure of the disc portion, the basket structure of the blade portion, and the gradual transition structure of the connection portion of the formed bladed disk exhibit a gradient dual structure / dual property distribution.

[0015] Preferably, the forging temperature range in the controllable strain isothermal forging in S3 is 700–880°C, and the radial movement speed range of the upper and lower punches is 0.05–0.4 mm / min.

[0016] Beneficial effects of this invention:

[0017] In the die forging process, the basket structure of the preform disc portion is completely spheroidized to form an equiaxed structure, while the preform blade portion retains the basket structure without spheroidization. At the connection between the preform disc portion and the preform blade portion, gradual spheroidization along the diameter direction forms a gradual transition structure. This invention can achieve a gradient dual structure / dual property distribution of the formed impeller disc, including the equiaxed structure of the disc portion, the basket structure of the blade portion, and the gradual transition structure along the diameter direction at the connection portion, thereby improving the service performance and service life of the impeller parts. Attached Figure Description

[0018] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0019] Figure 1 This is the initial basket structure of TC18 titanium alloy in this invention.

[0020] Figure 2 This is a cross-sectional view of the controllable strain isothermal forging die in this invention;

[0021] Figure 3 This is a schematic diagram of the bladed disk preform in this invention;

[0022] Figure 4 This is a schematic diagram of the shaped bladed disk of the present invention.

[0023] Attached image captions:

[0024] 1-Upper punch, 2-Lower punch, 3-Upper punch gradient transition zone, 4-Lower punch gradient transition zone, 5-Upper die, 6-Forming cavity, 7-Blade disk preform, 8-Lower die, 9-Through hole, 10-Preform blade part, 11-Connecting part, 12-Disc part, 13-Blade part, 14-Preform disk part. Detailed Implementation

[0025] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0027] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0028] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0029] Reference Figures 1-4 According to a preferred embodiment of the present invention, a controllable strain isothermal forging die for a double-structured titanium alloy bladed disk is provided. The forming die includes a bladed disk preform 7, an upper concave die 5, a lower concave die 8, and several sets of punches. Each set of punches includes an upper punch 1 and a lower punch 2. The upper concave die 5 and the lower concave die 8 are provided with forming grooves. The two forming grooves, the upper punch 1, and the lower punch 2 are fastened together to form a forming cavity 6 for placing the bladed disk preform 7. The bladed disk preform 7 in the forming cavity 6 is formed into a bladed disk after controllable strain isothermal forging.

[0030] The formed bladed disk includes a connecting part 11, a disk part 12, and a blade part 13. The thickness of the disk part 12 is smaller than the thickness of the blade part 13 and the connecting part 13. The shapes of the connecting part 13, the blade part 11, and the disk part 12 are gradually transitioned. The upper punch 1 and the lower punch 2 are respectively provided with an upper punch gradient transition area 3 and a lower punch gradient transition area 4. The widths of the upper punch gradient transition area 3 and the lower punch gradient transition area 4 correspond to the gradient widths of the connecting part 11 and the blade part 13, and are used to control the shape of the disk part 12, the connecting part 11, and the blade part 13 of the formed bladed disk.

[0031] Specifically, the widths of the upper punch gradient transition zone 3 and the lower punch gradient transition zone 4 are based on the gradient widths of the connecting part 11 and the blade part 13 of the formed blade disk to be produced.

[0032] Furthermore, the bladed disk preform 7 includes a preformed disk portion 14 and a preformed blade portion 10. The bladed disk preform 7 has a disc-shaped shape with the preformed disk portion 14 protruding in the middle. The thickness and diameter length of the preformed blade portion 10 are equal to the thickness and diameter length of the blade portion 13, respectively.

[0033] Furthermore, the microstructure of both the preform wheel disk portion 14 and the preform blade portion 10 is a basket webbing structure.

[0034] Furthermore, the upper punch 1 with the upper punch gradient transition zone 3 and the lower punch 2 with the lower punch gradient transition zone 4 are driven by an external hydraulic device and squeezed into the forming cavity 6 through the through holes on the upper die 5 and the lower die 8 for controlled strain isothermal forging of the bladed disk preform 7.

[0035] Furthermore, the forming groove and the outer shapes of the upper die 5 and the lower die 8 are symmetrical. The upper die 5 and the lower die 8 are respectively provided with through holes 9 that move in conjunction with the upper punch 1 and the lower punch 2. The through holes 9 are connected to the forming cavity 6 and the outside world. The diameter of the through holes 9 is equal to the diameter of the upper punch 1 and the lower punch 2.

[0036] This invention provides a forming method for a controllable strain isothermal forging die for a double-structured titanium alloy bladed disk, the forming method comprising the following steps:

[0037] S1: Titanium alloy is pre-forged into bladed disk preform 7 by near-β forging method. The preform disk part 14 in the bladed disk preform 7 has different initial heights. The preform disk part 14 and the preform blade part 10 in the bladed disk preform 7 have a basket structure inside.

[0038] S2: The pre-forged bladed disk preform 7 in S1 is fastened into the forming cavity 6 formed by the two forming grooves, the upper punch 1 and the lower punch 2, and then subjected to controlled strain isothermal die forging.

[0039] S3: Driven by an external hydraulic device, the upper punch 1 and the lower punch 2 are extruded into the forming cavity 6 through the through holes on the upper die 5 and the lower die 8. At a specific temperature, the upper punch 1 and the lower punch 2 are isothermally extruded at the same extrusion rate to the preform disc portion 14 to the preset thickness. During the die forging process, the basket structure of the preform disc portion 14 is completely spheroidized to form an equiaxed structure, and the preform blade portion 10 does not undergo spheroidization and retains the basket structure. The connection between the preform disc portion 14 and the preform blade portion 10 gradually spheroidizes along the diameter direction to form a gradual transition structure, and finally the formed bladed disk is obtained. The equiaxed structure of the disc portion 12, the basket structure of the blade portion 13, and the gradual transition structure of the connection portion 11 of the obtained formed bladed disk exhibit a gradient dual structure / dual property distribution.

[0040] Furthermore, in S3, the forging temperature range of the controllable strain isothermal forging is 700–880℃, and the radial movement speed range of the upper punch 1 and the lower punch 2 is 0.05–0.4 mm / min.

[0041] In the die forging process, the basket structure of the preform disc portion 14 is completely spheroidized to form an equiaxed structure, while the preform blade portion 10 does not undergo spheroidization and retains the basket structure. The connection between the preform disc portion 14 and the preform blade portion 10 undergoes gradual spheroidization along the diameter direction to form a gradual transition structure. This invention can achieve a gradient dual structure / dual property distribution of the equiaxed structure of the disc portion 12, the basket structure of the blade portion 13, and the gradual transition structure along the diameter direction of the connection portion 11, thereby improving the service performance and service life of the bladed disk parts.

[0042] Example 1

[0043] This embodiment provides a method for controlled strain isothermal forging of a dual-structure titanium alloy bladed disk. Using the controlled strain isothermal forging die of the dual-structure titanium alloy bladed disk of this invention, a pre-formed disk blank 7 with a basket weave structure inside the pre-formed disk portion 14 and the pre-formed blade portion 10 is fitted into the forming cavity 6. An upper punch 1 is installed in the through hole 9 of an upper die 5, and a lower punch 2 is installed in the through hole 9 of a lower die 8. The controlled strain isothermal forging die and the bladed disk blank 7 are heated to 700–880°C and held at that temperature for 10 minutes. The upper punch 1 and the lower punch 2 are pressed at the same rate of 0.05–0.4 mm / min onto the bladed disk. The preform 7 is extruded to a preset position. During the extrusion process, the basket structure of the preform disc part 14 is completely spheroidized to form an equiaxed structure. The preform blade part 10 does not undergo spheroidization and retains the basket structure. The connection between the preform disc part 14 and the preform blade part 10 gradually spheroidizes along the diameter direction to form a gradual transition structure, and finally a formed bladed disk is obtained. The formed bladed disk forms a gradient dual structure / dual performance distribution of the equiaxed structure of the disc part 12, the basket structure of the blade part 13, and the gradual transition structure along the diameter direction of the connection part 11. The upper punch 1 and the lower punch 2 are removed, the upper die 5 and the lower die 8 are separated, and the formed bladed disk is removed.

[0044] After the formed impeller is removed, excess metal will enter the flash groove and form burrs during the controlled strain isothermal forging process. Therefore, it is necessary to cut and remove the burrs from the formed titanium alloy impeller so that the part shape meets the requirements.

[0045] In this embodiment, the heating for the controllable strain isothermal forging process is provided by an external heating and heat preservation device to ensure that the forging die and the bladed disk preform 7 are isothermally forged at a temperature of 700-880°C. This can be achieved by heating in an air furnace or a vacuum furnace (this technique is a conventional and mature technique in this field, and therefore will not be described in detail).

[0046] In this embodiment, the power source for the engagement force between the upper die 5 and the lower die 8 in this invention includes, but is not limited to, the following power sources. The engagement force between the upper die 5 and the lower die 8 is provided by an external hydraulic component to ensure contact between the upper die 5 and the lower die 8 and form a stable forming cavity 6. Alternatively, the engagement force can be provided by a pin locking device (the technical means of providing power through external hydraulic components and providing engagement force through pin locking devices are conventional and mature existing technologies in this technical field, and therefore will not be described in detail).

[0047] In this embodiment, the upper punch 1 and the lower punch 2 radially extrude the bladed disk preform 7 under the drive of external hydraulic components. The extrusion rate and extrusion stroke position of the upper punch 1 and the lower punch 2 are both realized by an external stroke control device.

[0048] Preferably, the extrusion power of the upper punch 1 and the lower punch 2 is provided by external hydraulic components, as long as it can drive the upper punch 1 and the lower punch 2 to extrude the bladed disk preform 7;

[0049] Furthermore, the extrusion stroke positions of the upper punch 1 and the lower punch 2 include, but are not limited to, those controlled by a stroke control device, as long as the upper punch 1 and the lower punch 2 can be extruded to a preset position.

[0050] It is understandable that external hydraulic components, stroke control devices, etc. are all conventional and mature existing technologies in this technical field, and therefore will not be described in detail.

[0051] In this embodiment, the height of the preform wheel disk portion 14 affects the degree of spheroidization of the basket structure of the wheel disk portion 12 after the impeller is formed. The height of the preform wheel disk portion 14 in this invention is set appropriately according to the principle of constant volume, as long as the spheroidization of the basket structure of the preform wheel disk portion 14 can be achieved.

[0052] It is worth noting that the present invention aims to provide a controllable strain isothermal forging die for a double-structure titanium alloy bladed disk and a method for producing double-structure titanium alloy bladed disk parts using the forming die. Therefore, only the forming aspect of the double-structure titanium alloy bladed disk is described. In actual forming, while using the die and forming method, a die frame of the same specification and other forming auxiliary equipment familiar to those skilled in the art should be selected according to the specific usage requirements.

[0053] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0054] The above description is only a preferred embodiment of the present invention. Any technical solution that achieves the purpose of the present invention by essentially the same means is within the protection scope of the present invention.

Claims

1. A forming method for a controllable strain isothermal forging die using a double-structured titanium alloy bladed disk, characterized in that: The mold includes a preform (7) of a bladed disk, an upper die (5), a lower die (8) and several sets of punches. Each set of punches includes an upper punch (1) and a lower punch (2). The upper die (5) and the lower die (8) are provided with forming grooves. The two forming grooves, the upper punch (1) and the lower punch (2) are fastened together to form a forming cavity (6) for placing the preform (7) of the bladed disk. The preform (7) of the bladed disk in the forming cavity (6) is formed into a bladed disk after being forged by controlled strain isothermal die forging. The preform (7) of the bladed disk includes a preformed disk part (14) and a preformed blade part (10). The preform (7) of the bladed disk is shaped like a disc with the preformed disk part (14) protruding in the middle. The thickness and diameter length of the preformed blade part (10) are equal to the thickness and diameter length of the blade part (13) of the formed bladed disk. The formed bladed disk includes a connecting part (11), a wheel part (12), and a blade part (13). The thickness of the wheel part (12) is smaller than that of the blade part (13) and the connecting part (13). The shape of the connecting part (13) is gradually transitioned to that of the blade part (11) and the wheel part (12). The upper punch (1) and the lower punch (2) are respectively provided with an upper punch gradient transition area (3) and a lower punch gradient transition area (4). The width of the upper punch gradient transition area (3) and the lower punch gradient transition area (4) corresponds to the gradient width of the connecting part (11) and the blade part (13), which is used to control the shape of the wheel part (12), the connecting part (11), and the blade part (13) of the formed bladed disk. The forming method of the mold includes the following steps: S1: Titanium alloy is pre-forged into bladed disk preform (7) by near-β forging method. The preformed disk part (14) and the preformed blade part (10) of the bladed disk preform (7) have a basket structure inside. S2: The pre-forged bladed disk preform (7) in S1 is fastened into the forming cavity (6) formed by the two forming grooves, the upper punch (1) and the lower punch (2) for controlled strain isothermal die forging. S3: The upper punch (1) and lower punch (2) are driven by the external hydraulic device and squeezed into the forming cavity (6) through the through holes on the upper die (5) and lower die (8). At a specific temperature, the upper punch (1) and lower punch (2) are isothermally extruded to the preform wheel disk part (14) at the same extrusion rate to the preset thickness. During the die forging process, the basket structure of the preform wheel disk part (14) is completely spheroidized to form an equiaxed structure. The preform blade part (10) does not undergo spheroidization and retains the basket structure. The connection between the preform wheel disk part (14) and the preform blade part (10) gradually spheroidizes along the diameter direction to form a gradual transition structure. Finally, the formed blade disk is obtained. The equiaxed structure of the wheel disk part (12), the basket structure of the blade part (13), and the gradual transition structure of the connection part (11) of the obtained formed blade disk are distributed in a gradient dual structure / dual performance.

2. The forming method of a controllable strain isothermal forging die using a double-structured titanium alloy bladed disk according to claim 1, characterized in that: The two forming grooves are symmetrical, the upper die (5) and the lower die (8) are symmetrical in shape, the through hole (9) is connected to the forming cavity (6) and the outside, and the diameter of the through hole (9) is equal to the diameter of the upper punch (1) and the lower punch (2).

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