Inflatable near-net forming method for titanium alloy complex-section annular part blank

Abstract

The invention belongs to the field of manufacturing of annular parts for aero-engines, and particularly relates to an inflatable near-net forming method for a titanium alloy complex-section annular part blank. According to the technical scheme, the method comprises the following steps that (1) a titanium alloy complex-section annular piece blank drawing is designed; 2) designing and preparing a constrained bulging die according to the blank drawing; (3) preparing an annular prefabricated blank according to the blank drawing; (4) the annular prefabricated blank is placed in a restrained bulging die, and non-deformation areas at the two ends are clamped, fixed and sealed; then switching on a power supply, and heating the annular preformed blank; after heating to a preset temperature, nitrogen is introduced into the restrained bulging die, and superplastic forming of the annular preformed blank is achieved under the action of high temperature and high pressure; and (6) after the annular preformed blank is formed, the mold is opened, the non-deformed clamping parts at the two ends are cut off, and a titanium alloy complex-section annular piece blank is obtained. According to the method, the follow-up machining allowance can be remarkably reduced, the machining period is shortened, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of manufacturing ring parts for aircraft engines, and in particular relates to a method for nearly net-shape forming of a titanium alloy complex-section ring part blank by gas expansion. Background Art

[0002] Ring parts are mainly used in key systems such as airflow control, temperature control, sealing, and load bearing in aircraft engines. They play supporting, connecting, and sealing roles, and play an important role in aircraft engines. Titanium alloys have a series of advantages such as low density, high specific strength, and corrosion resistance, and are widely used in aircraft engine ring parts.

[0003] At present, the manufacturing process of titanium alloy ring parts is mainly ring rolling blank + machining manufacturing. Among them, the ring blank is mainly manufactured by bar upsetting + punching + hole expansion + ring rolling. The whole process is relatively long, and the metallurgical quality of the forging requires strict control of the process parameters of each process. At the same time, the blank often has a large excess under the existing process, and in the subsequent machining stage, all of this excess needs to be removed to obtain the ring parts. From the forging blank to the final part, the material removal rate can be as high as 90% or more, which seriously increases the cost of the ring parts. At the same time, the large amount of material removal will also lead to many problems such as long processing cycle and easy deformation during processing.

[0004] In response to the above problems, the current solution is mainly to refine the design of the forging structure and change the traditional rectangular cross-section ring forgings into special-section ring forgings. However, due to the limitations of rolling equipment, etc., the ring forgings still cannot achieve near-net forming, and subsequent machining still requires cutting off a large amount of excess. Summary of the invention

[0005] The present invention provides a method for near-net-shape forming of titanium alloy complex-section annular parts by inflation. For titanium alloy, a material that is difficult to deform, the deformation resistance of the material can be effectively reduced. At the same time, through precise mold structure design, near-net-shape forming of complex thin-walled components can be achieved. The subsequent machining allowance can be significantly reduced, the machining cycle can be shortened, and the manufacturing cost can be reduced.

[0006] The technical solution of the present invention is as follows:

[0007] A method for near-net-shape forming of a titanium alloy complex-section annular part blank by gas expansion, comprising the following steps: 1) designing a titanium alloy complex-section annular part blank drawing; 2) designing and preparing a constrained expansion mold according to the blank drawing; 3) preparing an annular preform according to the blank drawing; 4) placing the annular preform in the constrained expansion mold, clamping and fixing the non-deformed areas at both ends and sealing them; then turning on the power supply to heat the annular preform; after heating to a predetermined temperature, introducing nitrogen into the constrained expansion mold to achieve superplastic forming of the annular preform under high temperature and high pressure; 6) after the annular preform is formed, opening the mold, cutting off the non-deformed clamping parts at both ends, and obtaining a titanium alloy complex-section annular part blank.

[0008] Furthermore, in the method for near-net-net forming of titanium alloy complex-section ring-shaped parts by inflation, in the step 1), according to the design drawing of the titanium alloy complex-section ring-shaped parts, the shape and structural characteristics of the titanium alloy complex-section ring-shaped parts are analyzed, the complex structure is simplified, the maximum thickness of the titanium alloy complex-section ring-shaped parts is taken as the blank thickness, and finally the blank drawing of the titanium alloy complex-section ring-shaped parts is determined.

[0009] Furthermore, in the method for near-net-shape forming of titanium alloy complex-section annular parts blanks by air expansion, in the step 2), the constrained expansion mold includes an annular forming seat and two expansion top covers, the inner wall of the annular forming seat is the part forming area, and the two expansion top covers are respectively installed at two circular openings of the annular forming seat; an air inlet hole is provided at the center of the expansion top cover, and an electric heating device is provided around the expansion top cover.

[0010] Furthermore, in the method for near-net-net forming of titanium alloy complex-section ring-shaped blanks by inflation, in the step 3), a titanium alloy plate is obtained by roll forming, the thickness of the plate is determined according to the wall thickness of the titanium alloy complex-section ring-shaped blank, and the deformation structure type of the plate meets the requirements of relevant standards for titanium alloy structure; according to the blank drawing, the plate is cut into slabs, and then the slabs are rolled into a ring shape, and welded into a ring-shaped preform by electron beam welding or laser welding.

[0011] The beneficial effects of the present invention are as follows: based on the superplasticity principle, the present invention uses the method of bulging to manufacture titanium alloy complex cross-section annular blanks. The forming method provided by the present invention can effectively reduce the deformation resistance of the material for titanium alloy, a difficult-to-deform material, and at the same time, through the precise mold structure design, it can achieve near-net forming of complex thin-walled components, which can significantly reduce the subsequent machining allowance, shorten the machining cycle, reduce the manufacturing cost, and realize short-process, low-cost, and high-efficiency manufacturing of blanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of near-net-shape forming of a preform by inflating in a constrained bulging die. DETAILED DESCRIPTION

[0013] like Figure 1 As shown, a method for near-net-shape forming of a titanium alloy complex-section annular blank by inflating includes the following steps:

[0014] 1) Design a rough drawing of a titanium alloy complex cross-section ring part; according to the design drawing of the titanium alloy complex cross-section ring part, analyze the shape and structural characteristics of the titanium alloy complex cross-section ring part, simplify its complex structure, and take the maximum thickness of the titanium alloy complex cross-section ring part as the rough drawing thickness to ensure uniform wall thickness during the subsequent bulging forming process, and finally determine the rough drawing of the titanium alloy complex cross-section ring part;

[0015] 2) According to the rough drawing, design and prepare the constrained bulging mold; the constrained bulging mold includes an annular forming seat 1 and two expansion top covers 3, the inner wall of the annular forming seat 1 is the part forming area, and the two expansion top covers 2 are respectively installed at the two round openings of the annular forming seat 1; an air inlet 3 is provided at the center of the expansion top cover 2, and an electric heating device is provided around the expansion top cover 2; transition treatment is performed at the right angle, and lubricant is applied to ensure smooth filling;

[0016] 3) According to the blank drawing, an annular preform is prepared; a titanium alloy plate is obtained by rolling forming, the thickness of the plate is determined according to the wall thickness of the titanium alloy complex cross-section ring part, and the deformation structure type of the plate meets the requirements of the relevant standards for the titanium alloy structure; according to the blank drawing, the plate is cut into slabs, and then the slabs are rolled into a ring, and welded into an annular preform 4 by electron beam welding or laser welding; the welding strength and the roundness of the annular preform 4 need to be ensured;

[0017] 4) placing the annular preform 4 in the annular forming seat 1, and clamping and fixing the non-deformed areas at both ends of the annular preform 4 with two expansion top covers 3 and sealing them; then turning on the power supply, and heating the annular preform 4 through the electric heating device; after being heated to a predetermined temperature, nitrogen is introduced into the constrained bulging mold through the air inlet 3, and superplastic forming of the annular preform 4 is achieved under high temperature and high pressure;

[0018] 5) After the preform 4 is formed, the mold is opened, and the undeformed clamping parts at both ends are cut off to obtain a titanium alloy complex cross-section ring blank.

Claims

1. A method for near-net-shape forming of a titanium alloy complex cross-section ring blank by inflating, characterized in that: The method comprises the following steps: 1) designing a blank drawing of a titanium alloy complex cross-section annular part; 2) designing and preparing a constrained bulging die according to the blank drawing; 3) preparing an annular preform according to the blank drawing; 4) placing the annular preform in the constrained bulging die, clamping and fixing the non-deformed areas at both ends and sealing them; then turning on the power supply to heat the annular preform; after being heated to a predetermined temperature, introducing nitrogen into the constrained bulging die to realize superplastic forming of the annular preform under the action of high temperature and high pressure; 5) After the annular preform is formed, the mold is opened, and the undeformed clamping parts at both ends are cut off to obtain a titanium alloy complex cross-section annular blank.

2. The method for near-net-shape forming of titanium alloy complex-section annular blank by inflating according to claim 1, characterized in that: In the step 1), according to the design drawing of the titanium alloy complex cross-section ring part, the shape and structural characteristics of the titanium alloy complex cross-section ring part are analyzed, its complex structure is simplified, the maximum thickness of the titanium alloy complex cross-section ring part is taken as the blank thickness, and finally the blank drawing of the titanium alloy complex cross-section ring part is determined.

3. The method for near-net-shape forming of titanium alloy complex-section annular blank by inflating according to claim 1, characterized in that: In the step 2), the constrained bulging mold includes an annular forming seat and two expansion top covers, the inner wall of the annular forming seat is the part forming area, and the two expansion top covers are respectively installed at the two circular openings of the annular forming seat; an air inlet is provided at the center of the expansion top cover, and an electric heating device is provided around the expansion top cover.

4. The method for near-net-shape forming of titanium alloy complex-section annular blank by inflating according to claim 1, characterized in that: In the step 3), a titanium alloy plate is obtained by roll forming, the thickness of the plate is determined according to the wall thickness of a titanium alloy complex cross-section ring part, and the deformation structure type of the plate meets the requirements of relevant standards for titanium alloy structure; according to the blank drawing, the plate is cut into slabs, and then the slabs are rolled into a ring shape, and welded into a ring-shaped preform by electron beam welding or laser welding.

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