Integral forming method of titanium alloy variable-bus thin-walled cylinder segment component

Abstract

The application belongs to the technical field of part forming, and particularly relates to a titanium alloy variable web thin-walled cylinder segment component integral forming method, which solves the problems of difficult block assembly welding, many welds, poor precision, large springback in direct spinning, uneven stress and casting rolling machining limitations of the component, and comprises the following steps: step S1, spinning forming a straight cone cylinder, sizing according to target parameters, shearing and spinning after composite heating of a round blank; step S2, turning finishing, adhering the straight cone cylinder to a core mold, finishing the spinning trace and ultrasonic thickness measurement; step S3, high-temperature gas expansion, the straight cone cylinder is put into a variable web gas expansion mold, high-pressure inert gas is filled after heating to expand and adhere to the mold, and the finished product is obtained by pressure removal of the remaining edge. The application realizes integral welding-free forming, improves strength and precision, improves springback stress, and meets the demand of aerospace large thin-walled titanium alloy lightweight.

Description

Technical Field

[0001] This invention belongs to the field of parts forming technology, specifically, it relates to a method for integral forming of a titanium alloy variable busbar thin-walled cylindrical section component. Background Technology

[0002] Spinning, as an advanced plastic forming method, has been widely used in the manufacture of thin-walled rotating components in the aerospace field due to its advantages of simple molds, flexible processes, near-net-shape forming capabilities, and improved workpiece microstructure and properties. It has become the preferred forming method for thin-walled, weld-free rotating components. Compared to conventional machining, spinning also offers high efficiency, economy, and energy savings when processing complex curved thin-walled components, making it valuable in both civilian and defense applications.

[0003] With the increasing urgency for lightweight and high-performance weaponry, titanium alloys, due to their high specific strength and high thermal strength, are widely used in key components of new equipment. At the same time, adopting an integral thin-walled structure design can further improve the strength of key load-bearing components and achieve weight reduction goals. Therefore, the demand for manufacturing large thin-walled titanium alloy integral lightweight structures is becoming increasingly prominent.

[0004] In the existing technology, there are various technical solutions for forming thin-walled titanium alloy components. Among them, Chinese invention patent CN110125229A discloses a spinning forming method for thin-walled cylindrical titanium alloy parts. This method effectively improves the problems of poor plasticity and high forming difficulty of titanium alloy materials by optimizing the support structure of the spinning mandrel and the motion trajectory parameters of the spinning wheel, combined with local heating control during the spinning process, and successfully realizes the forming of thin-walled straight cylindrical and simple conical cylindrical parts of titanium alloy. However, this patented technology still has significant limitations: its core revolves around a single spinning process, which is mainly suitable for regular-shaped thin-walled components with straight generatrices. For thin-walled cylindrical components with variable generatrices (i.e., complex curved cylindrical sections with non-straight generatrices, such as parabolic or circular arc generatrices), this method cannot solve the problem of uneven material flow during the forming process. Specifically, the component has a large springback after forming, which causes the deviation between the actual contour and the design contour to exceed the allowable range of precision manufacturing. Furthermore, the residual stress distribution is concentrated and uneven, which can easily cause deformation or even cracking due to stress release during subsequent assembly or service, making it difficult to meet the precision forming requirements of thin-walled cylindrical sections with variable generatrices.

[0005] In addition to the aforementioned patented technologies, existing forming methods for thin-walled titanium alloy rotating parts also have the following drawbacks:

[0006] Sheet metal coil welding: This is a commonly used forming method. However, due to the presence of longitudinal welds in the components, the strength of the weld area is significantly lower than that of the base material, which cannot meet the high load-bearing requirements of key components in aerospace equipment. Furthermore, the weld area is prone to corrosion and fatigue failure.

[0007] Casting: Due to the limitations of titanium alloy casting performance, it is difficult to control the uniformity of wall thickness of thin-walled components during casting. Furthermore, defects such as porosity, inclusions, and shrinkage are easily generated inside the casting, resulting in unstable mechanical properties of the components and failing to meet the wall thickness accuracy and strength requirements of thin-walled cylinder sections.

[0008] Roll forming: This process is limited by equipment capacity and part structure, and can only be adapted to regular shaped components with a specific diameter range. It cannot adapt to the complex curved surface profile of thin-walled cylindrical sections with variable generatrices, and has extremely poor forming flexibility.

[0009] Machining: Although it can guarantee a certain dimensional accuracy, it is limited by the length of the part (machining vibration is easily generated when the length-to-diameter ratio is too large), and the material removal rate is high (usually exceeding 60%), resulting in high manufacturing costs and low production efficiency, which does not conform to the development trend of "near net-shape forming" of lightweight components.

[0010] Traditional segmented forming + welding: For thin-walled cylindrical components with variable busbars, some existing technologies use segmented processing followed by welding to manufacture them. However, this method has problems such as difficulty in positioning and welding, a large number of welds (multiple welds are prone to forming stress concentration areas), and poor overall contour accuracy, resulting in a significant decrease in the overall stiffness and fatigue resistance of the components.

[0011] In summary, with the continuous improvement of the performance indicators of aerospace equipment, the demand for titanium alloy variable busbar thin-walled cylindrical components is becoming increasingly urgent. However, existing technologies (including the single spinning process of patent CN110125229A and other forming methods) cannot solve the problem of low-stress, low-pressure precision forming of such components, making it difficult to meet the high-performance and high-reliability requirements of key structural components in aerospace vehicle development. Therefore, it is urgent to develop an integral forming method for titanium alloy variable busbar thin-walled cylindrical components to overcome the shortcomings of existing technologies and improve the manufacturing level and support capabilities of key components for aerospace equipment. Summary of the Invention

[0012] To address the shortcomings of existing technologies, the present invention aims to provide an integral forming method for titanium alloy variable busbar thin-walled cylindrical sections, overcoming the problems of high welding difficulty, numerous welds, and poor contour accuracy in the traditional segmented forming and welding manufacturing method for titanium alloy variable busbar thin-walled conical cylinders, as well as the large springback amount and uneven residual stress distribution in direct spinning of titanium alloy variable busbar thin-walled cylindrical sections.

[0013] A method for integral forming of a thin-walled cylindrical section component with variable busbar according to the present invention includes the following steps:

[0014] Step S1: Spin forming of titanium alloy straight tapered cylinder:

[0015] Based on the generatrix curve, cone angle, and wall thickness requirements of the target variable generatrix cone, the dimensional parameters of the straight cone intermediate are determined through unfolding calculations. Based on the principle of constant volume, combined with finite element numerical simulation, the thickness distribution of the variable thickness circular billet is calculated. The variable thickness circular billet is fixed to the spinning mandrel through the tail end, and the variable thickness circular billet is preheated as a whole using a flame heating gun. At the same time, the working area of ​​the spinning wheel is locally heated by a laser heater. A radial force is applied by the spinning wheel, causing the variable thickness circular billet to be sheared and spun along the spinning mandrel surface, thinning and deforming to form a thin-walled straight cone.

[0016] Step S2: Turning of the outer surface of the titanium alloy straight tapered cylinder:

[0017] After spinning, the titanium alloy straight tapered cylinder remains in contact with the spinning mandrel under the action of the tail jack; the spinning wheel on the spinning equipment is replaced with a carbide turning tool to machine and repair the spinning marks on the outer surface of the titanium alloy straight tapered cylinder; at the same time, an ultrasonic thickness gauge is used to monitor the wall thickness of the titanium alloy straight tapered cylinder in real time and meet the profile requirements.

[0018] Step S3: High-temperature gas expansion forming of titanium alloy variable busbar thin-walled cone cylinder:

[0019] The machined titanium alloy straight tapered cylinder is placed in an air-expanding mold with a variable generatrix inner surface. A press is used to press a grooved cover plate against the flange edge of the titanium alloy straight tapered cylinder to seal the air-expanding mold. The titanium alloy straight tapered cylinder and the air-expanding mold are electromagnetically heated by an induction coil surrounding the air-expanding mold. High-pressure inert gas is injected into the mold cavity through the air inlet of the cover plate, forcing the titanium alloy straight tapered cylinder to expand radially to completely fit the inner surface of the air-expanding mold. After pressure holding and cooling, the pressure is released, the mold is opened, and the excess material is removed to obtain a titanium alloy variable generatrix thin-walled tapered cylinder.

[0020] Furthermore, in step S1, the variable thickness round blank is preheated as a whole using a flame heating gun.

[0021] Furthermore, in step S1, the spinning method for the variable thickness round blank is shear spinning along the spinning mandrel surface.

[0022] Furthermore, in step S1, the spinning method for the variable thickness round blank is shear spinning along the spinning mandrel surface.

[0023] Furthermore, in step S2, the titanium alloy straight tapered cylinder maintains a close fit with the spinning mandrel during turning and finishing, and the fit is achieved through the action of the tail tip.

[0024] Furthermore, in step S3, the air-expansion mold has a variable generatrix inner surface, and the machined titanium alloy straight tapered cylinder is placed in the variable generatrix inner surface.

[0025] Furthermore, in step S3, the cover plate has a groove, which is used to engage and press against the flange edge of the titanium alloy straight tapered cylinder.

[0026] Furthermore, in step S3, high-pressure inert gas is injected into the mold cavity through the air inlet of the cover plate.

[0027] Furthermore, in step S3, the goal of radial expansion of the titanium alloy straight tapered cylinder is to completely conform to the inner surface of the air expansion mold.

[0028] Furthermore, after pressure holding and cooling, the pressure release and mold opening, as well as the removal of excess material, need to be performed sequentially to obtain a titanium alloy variable busbar thin-walled conical cylinder.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention enables the integral forming of thin-walled cylindrical components of titanium alloy variable busbars, abandoning the traditional manufacturing method of segmented forming + welding, effectively reducing the number of welds and reducing the difficulty of assembly and welding, while improving the component outline accuracy and overall strength, and overcoming the problem of strength reduction caused by longitudinal welds in plate roll welding.

[0031] 2. Compared with the direct spinning process of thin-walled cylindrical sections of titanium alloy variable busbars, this invention significantly improves the defects of large springback and uneven distribution of residual stress by combining the processes of spinning, turning and air expansion, and achieves precision forming of fewer components without stress.

[0032] 3. This invention combines the advantages of simple molds and flexible processes of spinning, avoiding the problems of casting forming being difficult to meet wall thickness requirements, rolling forming being limited by diameter and shape, and machining being constrained by length and costly. It takes into account both forming efficiency and economy, and can meet the manufacturing needs of aerospace equipment for large thin-walled titanium alloy integral lightweight structures. Attached Figure Description

[0033] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0034] Figure 1 This is a schematic diagram of the titanium alloy straight tapered cylinder spinning process in this invention;

[0035] Figure 2 This is a schematic diagram of the turning process of a titanium alloy straight tapered cylinder in this invention;

[0036] Figure 3 This is a schematic diagram of the gas expansion forming of the titanium alloy variable busbar cone in this invention;

[0037] Figure 4 This is a schematic diagram of the titanium alloy variable busbar tapered cylinder part in this invention.

[0038] The following are the labeling elements in the figure:

[0039] Detailed Implementation

[0040] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0041] This invention provides a method for integral forming of a thin-walled cylindrical section component with a variable busbar in titanium alloy, comprising the following steps:

[0042] Step S1: Spin forming of titanium alloy straight tapered cylinder:

[0043] like Figure 1 As shown, based on the generatrix curve, cone angle, and wall thickness requirements of the target variable generatrix cone, the dimensional parameters of the straight cone intermediate are determined by unfolding calculation; based on the principle of constant volume, combined with finite element numerical simulation, the thickness distribution of the variable thickness round blank 2 is calculated; the variable thickness round blank 2 is fixed to the spinning mandrel 1 by the tail 6, and the titanium alloy variable thickness round blank 2 is preheated as a whole by the flame heating gun 4, while the working area of ​​the spinning wheel 3 is locally heated by the laser 5; the radial force is applied by the spinning wheel 3, so that the variable thickness round blank 2 is sheared and spun along the surface of the spinning mandrel 1, thinning and deforming it to form a thin-walled straight cone;

[0044] Step S2: Turning of the outer surface of the titanium alloy straight tapered cylinder:

[0045] like Figure 2 As shown, after spinning, the titanium alloy straight tapered cylinder 7 remains in contact with the spinning mandrel 1 under the action of the tail jack 6; the spinning wheel 3 on the spinning equipment is replaced with a carbide cutting tool 8 to machine and repair the spinning marks on the outer surface of the titanium alloy straight tapered cylinder 7; at the same time, an ultrasonic thickness gauge is used to monitor the wall thickness of the titanium alloy straight tapered cylinder 7 in real time and meet the profile requirements.

[0046] Step S3: High-temperature gas expansion forming of titanium alloy variable busbar thin-walled cone cylinder:

[0047] like Figure 3 As shown, the machined titanium alloy straight tapered cylinder 7 is placed in an air-expanding mold 10 with a variable generatrix inner surface. The grooved cover plate 9 is pressed against the flange edge of the titanium alloy straight tapered cylinder 7 by a press to seal the air-expanding mold 10. The titanium alloy straight tapered cylinder 7 and the air-expanding mold 10 are electromagnetically heated by an induction coil 11 surrounding the air-expanding mold 10. High-pressure inert gas is injected into the mold cavity through the air inlet of the cover plate 9, forcing the titanium alloy straight tapered cylinder 7 to expand radially until it completely fits the inner surface of the air-expanding mold 10, thereby achieving rapid and precise forming of the titanium alloy variable generatrix tapered cylinder.

[0048] like Figure 4 As shown, after holding pressure and cooling, the pressure is released and the mold is opened. The excess material from the process is removed to obtain a titanium alloy variable generatrix thin-walled cone 12.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 limitations on this application.

[0050] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for integral forming of a thin-walled cylindrical section component with a variable busbar of titanium alloy, characterized in that, Includes the following steps: Step S1: Spin forming of titanium alloy straight tapered cylinder: Based on the generatrix curve, cone angle, and wall thickness requirements of the target variable generatrix cone, the dimensional parameters of the straight cone intermediate part are determined through unfolding calculations. Based on the principle of constant volume, combined with finite element numerical simulation, the thickness distribution of the variable thickness round blank (2) is calculated; the variable thickness round blank (2) is fixed to the spinning mandrel (1) by the tail top (6), and the variable thickness round blank (2) is preheated as a whole by the flame heating gun (4), while the working area of ​​the spinning wheel (3) is locally heated by the laser heater (5); the radial force is applied by the spinning wheel (3) to make the variable thickness round blank (2) shear and spin along the surface of the spinning mandrel (1) to reduce the thickness and form a thin-walled straight cone cylinder; Step S2: Turning the outer surface of the titanium alloy straight tapered cylinder: After spinning, the titanium alloy straight tapered cylinder (7) is kept in contact with the spinning mandrel (1) under the action of the tail (6); the spinning wheel (3) on the spinning equipment is replaced with a carbide turning tool (8) to machine and repair the spinning marks on the outer surface of the titanium alloy straight tapered cylinder (7); at the same time, an ultrasonic thickness gauge is used to monitor the wall thickness of the titanium alloy straight tapered cylinder (7) in real time and meet the profile requirements; Step S3: High-temperature gas expansion forming of titanium alloy variable busbar thin-walled cone cylinder: The machined titanium alloy straight tapered cylinder (7) is placed in an air expansion mold (10) with a variable generatrix inner surface. The grooved cover plate (9) is pressed against the flange edge of the titanium alloy straight tapered cylinder (7) by a press to seal the air expansion mold (10). The titanium alloy straight tapered cylinder (7) and the air expansion mold (10) are electromagnetically heated by an induction coil (11) surrounding the air expansion mold (10). High-pressure inert gas is injected into the mold cavity through the air inlet of the cover plate (9) to force the titanium alloy straight tapered cylinder (7) to expand radially to completely fit the inner surface of the air expansion mold (10). After pressure holding and cooling, the pressure is released, the mold is opened, and the process excess is removed to obtain a titanium alloy variable generatrix thin-walled tapered cylinder (12).

2. The integral forming method for thin-walled cylindrical sections of titanium alloy variable busbars according to claim 1, characterized in that, In step S1, the variable thickness round blank (2) is preheated by a flame heating gun (4) for overall preheating.

3. The integral forming method for thin-walled cylindrical sections of titanium alloy variable busbars according to claim 1, characterized in that, In step S1, the spinning method of the variable thickness round blank (2) is to shear and spin along the surface of the spinning core mold (1).

4. The integral forming method for thin-walled cylindrical sections of titanium alloy variable busbars according to claim 1, characterized in that, In step S1, the spinning method of the variable thickness round blank (2) is to shear and spin along the surface of the spinning core mold (1).

5. The integral forming method for thin-walled cylindrical sections of titanium alloy variable busbars according to claim 1, characterized in that, In step S2, the titanium alloy straight tapered cylinder (7) is kept in contact with the spinning mandrel (1) during turning and finishing. The contact is achieved by the action of the tail top (6).

6. The integral forming method for thin-walled cylindrical sections of titanium alloy variable busbars according to claim 1, characterized in that, In step S3, the air expansion mold (10) has a variable generatrix inner surface, and the machined titanium alloy straight tapered cylinder (7) is placed in the variable generatrix inner surface.

7. The integral forming method for a thin-walled cylindrical section component of a titanium alloy variable busbar according to claim 1, characterized in that, In step S3, the cover plate (9) has a groove, which is used to fit and press the flange edge of the titanium alloy straight tapered cylinder (7).

8. The method for integral forming of a thin-walled cylindrical section component of titanium alloy variable busbar according to claim 1, characterized in that, In step S3, high-pressure inert gas is injected into the mold cavity through the air inlet of the cover plate (9).

9. The method for integral forming of a thin-walled cylindrical section component of titanium alloy variable busbar according to claim 1, characterized in that, In step S3, the goal of radial expansion of the titanium alloy straight cone (7) is to completely fit the inner surface of the air expansion mold (10).

10. The method for integral forming of a thin-walled cylindrical section component of titanium alloy variable busbar according to claim 1, characterized in that, After pressure holding and cooling, the pressure release and mold opening and the removal of process excess edges need to be performed in sequence to obtain a titanium alloy variable busbar thin-walled cone (12).

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